With the intensification of global climate change and land salinization, improving the ability of rice (Oryza sativa L.) to grow in saline and alkaline environments has become a key challenge for agricultural production. The realization of the strategy of " the adaptation of germplasm to land " requires a deep understanding of the salt tolerance mechanism of rice, then breeding improvement on this basis. In this study, we summarized the recent research results on salt tolerance regulatory genes in rice, and classified them functionally according to the biological processes involved. The perception of salt stress in rice and the subsequent activation of various physiological regulatory mechanisms, including osmotic regulation, ion homeostasis, antioxidant defense system and nutrient balance, were analyzed in detail. In this review, we focus on several key Salt stress signaling pathways in rice, including the SOS (Salt Overly Sensitive) pathway, MAPK (Mitogen-Activated Protein Kinase) cascade pathway and hormone regulatory pathway. These pathways play crucial roles in rice adaptation salt stress environment. By reviewing the existing literature, this review aims to provide a comprehensive overview of the salt tolerance regulatory genes and their functions in rice, provide scientific basis on breeding salt-tolerant rice on these grounds, and as a reference in improving the yield and quality of rice under saline and alkaline environments.

Rice grain filling is the most important physiological process of grain formation, and it is also the decisive stage of grain weight, yield and rice quality. To fully understand the intrinsic characteristics of rice grain filling and promote high-yield cultivation and good quality breeding of rice, the biological characteristics, physiological mechanism, endogenous hormones, enzyme activities, gene, proteins and environmental factors affecting rice grain filling are summarized. Meanwhile, the research direction of rice grain filling is discussed, and the possibility of studying grain filling mechanism in molecular biology such as proteomics, genomics and gene expression is also put forward.

Leaf, as the material basis for constructing the rice organs, is closely related to the quality of the light environment and the utilization rate of light energy. The leaf area index (LAI) is an important indicator related to rice yield, and is significantly correlated with the light and effective radiation absorption coefficient in rice canopy. In this paper, we reviewed the relationship between the LAI in different growth periods of rice and the yield, and pointed out that the optimal LAI could be increased based on variety selection and cultivation measures, to achieve the high yield. The study could provide a theoretical basis for developing a predicting system of the optimal LAI and for regulating the rational canopy structure of rice.

Zinc (Zn) is an essential micronutrient for animals and plants. Zinc deficiency or excess can seriously affect the growth and development of rice. Maintaining zinc content in rice at a certain level is helpful to improve the yield and quality of rice, increase the zinc content in grain, and solve the current problem of zinc deficiency in human body to a certain extent. Therefore, it is important to understand Zn uptake, transport, distribution, and other molecular mechanisms regulating Zn homeostasis in rice. In this review, we briefly summarized the importance of zinc in plants, especially the ion transporters in rice and the molecular mechanisms. The roles of these ion transporters in the uptake of Zn from soil, the transport from root to shoot, and the distribution of Zn to various parts of rice were summarized. Some molecular mechanisms related to ion transporters were also summarized. This study provides reference for the mining of zinc homeostasis regulatory genes in rice, the study of molecular mechanism, and the creation of high zinc rice germplasm.

This review provides a theoretical basis for iron bio-fortification and low absorption accumulation of pollutants of rice. It summarizes the available research literatures about iron plaque for recent five years, including: ①the concept of iron plaque; ②the location of iron plaque; ③the characteristics of iron plaque; ④the factors affecting the formation of iron plaque; ⑤the environmental and ecological function of iron plaque; ⑥the molecular mechanism of iron plaque. At last, future research directions of iron plaque are discussed.

【Objective】Barnyard grass (Echinochloa crus-galli) is one of the main malignant weeds in rice fields in China. Acetolactate synthase (ALS) inhibitors, such as penoxsulam, are the main herbicides for controlling E. crus-galli in rice fields. Previously, our research team identified a suspected penoxsulam-resistant E. crus-galli population, AHTC-01, in the main rice production area of Tianchang City, Anhui Province, China. The objective of this study is to clarify its resistance levels to major herbicides, investigate the possible resistance molecular mechanisms, and to provide a theoretical basis for the effective control of resistant E. crus-galli and the delay of further development of herbicide resistance.【Method】Using the greenhouse potting method, the resistance levels of AHTC-01 to penoxsulam and its resistance patterns to different herbicides were determined at the whole-plant level. The target resistance molecular mechanism was explored through target gene sequencing and real-time quantitative PCR (RT-qPCR) analysis.【Result】Compared with the susceptible E. crus-galli population AHFY-01, the suspected resistant population AHTC-01 had developed high-level resistance to penoxsulam, with a resistance index (RI) of 620. Analysis of the target-site based resistance mechanisms showed that the ALS2 gene copy in the AHTC-01 population had a mutation from tryptophan (Trp) to leucine (Leu) at codon position 574, with a population mutation frequency of 100%. At 12 h after penoxsulam treatment, the relative expression level of ALS in the resistant E. crus-galli population AHTC-01 was 2.26 times of that in the susceptible E. crus-galli population AHFY-01. AHTC-01 also exhibited varying levels of cross-resistance to three other ALS inhibitors, bispyribac sodium, pyribenzoxim, and imazamox, with RIs of 8.24, 13.36, and 20.36, respectively. However, it remained susceptible to other herbicides with different modes of action (MOAs), including the acetyl-CoA carboxylase (ACCase) inhibitors cyhalofop-butyl, fenoxaprop-P-ethyl, and clethodim, the 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor tripyrasulfone, and the synthetic auxin mimic florpyrauxifen-benzyl.【Conclusion】Mutation of the ALS2 at amino acid position 574 and ALS overexpression are one of the main reasons for the resistance of E. crus-galli population AHTC-01 to penoxsulam, which also confers cross-resistance to different ALS inhibitors. In actual agricultural production, effective control of this type of resistant E. crus-galli can still be achieved by rotating the use of other herbicides with different MOAs.

Chalkiness is one of the important indexes to evaluate the appearance quality of rice. It is a bad character that seriously affects the grinding, appearance and taste quality of rice, and plays an important role in the market value evaluation of rice. This paper summarized the effects of environmental factors, physiological mechanisms and genetic mechanisms on the formation of chalkiness in rice, and pointed out the difficulties existing in the improvement of chalkiness in rice breeding. Based on the current research results and the development of related technologies, some suggestions for improvement were put forward to provide a certain research basis for the production of high-quality rice.

Rice yield has been stagnant in recent years, and the construction and optimization of the ideal plant type can create new possibilities for the improvement of rice yield. To strengthen the research on the breeding of rice ideal plant type, the classical models of five kinds of rice ideal plant types are summarized, and the morphological characteristics of root, stem, leaf, and panicle of rice are analyzed. This paper lists the related genes and their regulatory networks found at home and abroad in recent years which affect rice plant types, and puts forward future development trends in rice breeding.

The research overviews the morphology of rice roots, functions and vigor of rice roots, relationships between rice roots and aboveground parts and yield, and the impact of environmental factors on roots, and analyzes the impact of root growth and characteristics on quality and yield of rice, concludes that rice roots respond differently to the quality and yield of rice through itself and the impact of environmental factors. The analysis shows that it is of great significance to carry out more research on the root index of rice, strengthen the research of modern molecular biology techniques in rice roots, and improve roots study, in order to provide further guidance rice production.

To better prevent and control the occurrence of rice blast and provide the scientific basis for rice breeding and drug discovery, it is very necessary to explore the mechanism of interaction between Magnaporthe oryzae and rice. In this paper, the mechanism of M. oryzae infecting rice, the signal recognition and downstream response of rice to M. oryzae infection and the defense response mechanism induced by the fungi were summarized, and the expression and regulation of defense-related genes in rice and the molecular breeding strategies for improving rice disease resistance were analyzed. After M. oryzae infection, rice plant could resist the infection by self-defensive systemic response, such as thickening cell wall, expression of pathogenesis-related proteins and programmed cell death at the invasion site of M. oryzae, etc. It is pointed out that using genetic engineering means to induce plant immune response to resist the harm of M. oryzae has important practical significance, and it is also the most effective and cost-optimal method to control rice blast. Moreover, as a model system to study the pathogen-plant interaction, deeply understand the interaction mechanism between M. oryzae and rice can provide a scientific basis for the prevention and control of other important fungal diseases by inducing the expression of rice defense genes.

Guangdong is located in the subtropical zone with high temperature and long sunshine hours, which has natural climate conditions for high quality and high yield of rice, and a long history of rice cultivation. As one of China’s 13 major grain production areas, Guangdong has brilliant achievements named as the ‘Guangdong rice phenomenon’ since the dwarf varieties’ breeding. However, over the years, Guangdong has relatively high dependence on rice from other areas because the self-sufficiency rate of rice in Guangdong is just about 30%. With the outbreak of COVID-19, the rice security of Guangdong is affected to a certain degree. This study investigated the current situation of rice production in Guangdong and analyzed the existing problems by referring to relevant materials such as China Agricultural Statistical Yearbook, Guangdong Statistical Yearbook and Guangdong Rural Statistical Yearbook, et al. Suggestions were put forward to promote the development of rice industry through policy guidance, strengthening the breeding of breakthrough varieties, building a perfect extension and demonstration system, digitizing marketing channels and extending the value chain of rice.

The aim of this study was to provide reference for the functional study of early nodulation protein ENOD93 in non-legumes. In this study, bioinformatics method was used to identify rice ENOD93 gene family. The physical and chemical properties, chromosome location, gene structure, protein structure, expression spectrum and evolutionary relationship of the members were analyzed. The results showed that there were 7 members of rice ENOD93 gene family, which were distributed on chromosomes 2 and 6, and the gene structure was relatively simple. Moreover, most ENOD93 genes are highly similar in the distribution and arrangement of conserved domain and motif. The results of RNA-Seq data analysis showed that ENOD93 gene family was highly expressed in pistils, seeds and embryos, and the expression level of some gene was induced by stress. Based on the phylogenetic analysis of nine monocotyledonous and dicotyledonous species, 31 ENOD93 gene family members were divided into four distinct groups. The expression of ENOD93 gene in rice was different in different tissues and at different developmental stages, and some genes were induced by stress, suggesting that ENOD93gene family was involved in the development process of many plant tissues and played an important role in the response to stress.

It has been more than thirty years since the first study of high temperature (HT) stress tolerant rice breeding was carried out by scientists from the International Rice Research Institute (IRRI). Studies such as disaster assessment and prediction of HT, HT tolerant breeding, rice plant morphological development, yield, quality, physiological and biochemical responses to HT stress, prevention and control under stress condition, and genetic improvement of rice varieties tolerant to HT have been conducted by scientists worldwide with great progress. This article briefly reviews the research progress regarding HT in rice, focuses on reviewing the effects of HT stress on rice growth and physiological responses, combined effects of other environmental factors with HT on rice, and possible heat tolerance/heat response mechanisms in rice. This review could provide a reference for future studies on HT stress tolerance in rice.

Total RNA isolation from rice seeds plays an important role in the molecular genetic basic experiments of rice. However, it is difficult to obtain high-quality rice seed RNA, which hinders the construction of cDNA library, RNA Seq and gene expression analysis. In order to explore the relevant impact factors of total RNA isolation from rice seeds and find the appropriate isolation methods, this study compared three different isolation methods, including Trizol method, GeneMark Kit Method and Adlaid kit method, different consumable treatment methods, grinding methods and other different factors to improve the effect of total RNA isolation from rice seeds. Different tests results showed that the Aidlad Polysaccharide Extraction Kit isolated total RNA from rice seeds with complete 28S, 18S bands, low degradation and high purity. Among the different consumables treatment methods, the total RNA isolated by the proteinase K-treated consumables degraded less than the other two methods. Besides, the 28S and 18S bands were clearer and more complete, and the total RNA had the highest quality and the best effect. In the grinding methods, the liquid nitrogen freeze-grinding method could inhibit the degradation of RNA by RNase effectively. In this study, the analysis and improvement of the relative factors of rice seed RNA isolation process lays a certain technical foundation for promoting the molecular experiment of rice seed as the research object.

Duckweed (Lemna minor L.) is a floating microscopic plant that is usually found in standing water. Climate change is characterized by rising temperature, which is mainly due to increasing atmospheric CO₂ concentration, and it poses potential risks to food production. Owing to factors such as climate warming and/or the eutrophication of water, duckweed growth in paddy fields has shown an increasing trend year by year in China. This paper focused on the impacts of duckweed on paddy fields and highlighted some vital trends. Duckweed reduced the water temperature of paddy by 0.86-2.76 ℃ and the pH value by 0.10-0.45, changed the structure of microbial community, reduced the NH₃ volatilization by 18.2%-59.0%, and increased the nitrogen utilization rate by 17.2%-78.0%. As a result, the nitrogen sink of paddy increased and the rice yield rose by 9.0%-34.6% upon duckweed growing in paddy. Duckweed grew and reproduced rapidly, and its annual biomass could reach 8×10³-13×10³ kg·hm^-2, making its carbon sink almost equal to that of rice in the same season. The mutualism between duckweed and rice was greater than its competition, and the coexistence of duckweed and rice in paddy showed an adaptation of the rice field ecosystem to environmental changes. Future research in this field should focus on the effect and its mechanism of duckweed on the paddy environment changes, rice growth, yield, and quality, and the risks which might bring to the paddy fields, especially the interaction with environmental factors (elevated temperature and CO₂ concentration, etc.). Such research would provide theoretical support for the sustainable agricultural development of rice farming technology based on biological collaboration, such as rice-duckweed, which can adapt to future changes in climate and environment.

Interrelation was analyzed between meteorological conditions in different growth stages and yield components in Xinyang with hybrid rice Shanyou 63. The study showed the ear-bearing tiller percentage became higher while the ratio of productive tiller was about 300%, and appropriate daily mean temperature was 26℃, sunlight duration was 5.5h; panicle number was in direct ratio to sunlight duration in tillering stage, and it was not obvious for the change of panicle number while the sunlight duration was above 5h; there was a high panicle Number in booting stage while the temperature was from 28℃ to 30℃, and the daily range was from 8℃ to 10℃; high temperature (>30℃) and sunlight deficiency (<5h) would decrease the rice seed setting rate remarkably; the total sunlight duration, precipitation and daily range all had effects on the rice grain weight; the importance of each yield component was as follows: seed setting rate>panicle number>grain weight.

The self-sufficiency rate of edible vegetable oil is less than 31 percent in China, with a high degree of import dependence. Rapeseed is the only winter oilseed crop with a wide range of suitable planting region, and it is an important source of edible vegetable oil in China. Planting more rapeseed is an important measure to guarantee national edible oil supply security. Making full use of the winter fields in the southern double cropping rice area to promote “rice-rice-rapeseed” production is an important approach to expand the planting area of rapeseed. The area suitable for the “rice-rice-rapeseed” production mode is mainly distributed in the double cropping rice area of Hunan, Jiangxi, Guangxi and Hubei provinces in China, with a potential area of about 1.87 million hm². According to the conditions of temperature and light resources, three suitable areas for the “rice-rice-rapeseed” production include the ample area, tightly balanced area and the constrained area. All the areas require early-maturing rapeseed varieties with a growth period of around 180 days, which are suitable for being sown in mid- to late October and harvested in mid- to late April. Among a total of 75 new rapeseed lines participated in the early-maturity group of the national rapeseed variety trials from 2013 to 2022, the average growth period ranged from 169.3 to 185.5 days, and the average yield was 1 635.90-2 228.55 kg·hm^-2, with 22 varieties out yielded the check variety. There are 72 early-maturing winter oilseed rape varieties with a growth period less than 190 days were registered by the end of May 2023. These varieties are suitable to be used in the “rice-rice-rapeseed” mode, and most of them are hybrid varieties with low erucic acid and low glucosinolate quality. 11 varieties, Yangguang 131, Fengyou 730, Fengyou 320, Fengyou 847, Ganyouza 906, Shengguang 127, Xiangyou 420, Jingyou 69, Fengyou 112, Huayouza 652, Ganyouza 1009, are the most promoted and applied early-maturing winter rapeseed varieties in the “rice-rice-rapeseed” production area, with more than 135 hm² each in 2022. The present varieties can basically meet the early-maturation demand in the ample area. In the tightly balanced and constraint areas, however, the growth period of these varieties is too long. To expand the production and efficiency of rapeseed industry, it is urgently needed to strengthen the policy and financial security in the future, carry out joint breeding projects for short-growth-period winter rapeseed varieties to further improve the yield in the ample area and shorten the growth period in the tightly balanced and constrained areas. Meanwhile, to strengthen the research and promotion of supporting cultivation technology for elite varieties, match well early rice, late rice, and rapeseed varieties are also good measures to support the expansion of rapeseed production in the “rice-rice-rapeseed” production area. In addition, improving agricultural socialized services, expanding agricultural insurance and increasing subsidies for rapeseed planting to ensure production benefit will enhance the farmers’ enthusiasm for the “rice-rice-rapeseed” production.

The aim of this study is to identify the resistance of rice varieties from different ecological regions to rice blast, and to find an incidence index standard for evaluating rice blast. 72 rice varieties (lines) were used as materials for resistance identification. The plastic greenhouse artificial spray and natural induction of diseased plants’samples were combined to identify the disease. There were 17 rice varieties with strong resistance to blast disease in 72 rice varieties or lines tested, and their leaf blast disease index was 0-2. The other varieties or lines had more severe disease incidence, and the leaf blast disease index was more than 30, and some even died. The varieties with no disease in the seedling stage were also possible to be susceptible to panicle blast in the mature period. After transplanted to the field, the varieties with common type of leaf blast could be reversed to having no disease signs. The mortality of varieties with acute type of leaf blast was above 90% at reviving stage. It indicated that there was no significant correlation among seedling blast, leaf blast and panicle neck blast. The acute type leaf blast could be used as the incidence index standard for identifying the rice blast at seedling stage.

Abstract:To detect the activities of rice catalase ,ammonium molydate method is accurate, convenient and efficient .The reliability of the method was verified by using flag leaf of Neiliangyou 6 and Xiushui 09 and comparing the accuracy and the precision with ultraviolet absorption method.The first,the average of two method have no significent difference .The second, the Coefficient of Variation of ultraviolet absorption method respectively is 0.78% and 0.58%,and the Coefficient of Variation of ammonium molydate method respectively is 0.35% and 0.42％.

【Objective】The study investigated the impact of salicylic acid (SA) priming on the germination vigor and physiological response of rice seeds under low temperatures. It aimed to reveal the expression patterns of genes related to abscisic acid (ABA) and gibberellin (GA) metabolic pathways as well as cell wall relaxation genes by SA priming. This research provided a theoretical basis for the study of rice seed germination at low temperatures.【Method】Using indica three-line hybrid rice Taifengyou 208 seeds as materials, the effects of SA on seed germination vigor and physiology responses under low temperature were analyzed through seed priming treatment, and the expression patterns of genes related to ABA, GA and expansin in response to SA were analyzed by qRT-PCR.【Result】Low temperature (15 ℃) significantly delayed the germination process of rice seeds. In seeds germinated at low temperatures for one day, the endogenous SA concentration was 1.7 times higher than that at normal temperatures (28 ℃). However, for five-day-old seedlings, the SA concentration under low temperature was only 0.6% of that at normal temperatures. SA could effectively enhanced germination vigor of seeds at low temperature, with the most significant effects observed at 2 000 μmol·L^-1 SA. This concentration significantly increased the germination index, vigor index, shoot length, root length, fresh weight, and dry weight of seeds under low temperature conditions. Notably, the vigor index was three times that of non-primed seeds (CK1) and two times that of water-primed seeds (CK2). In terms of physiological indexes, SA priming increased the contents of soluble sugar, proline and active oxygen, enhanced the activities of total amylase, β-amylase, superoxide dismutase (SOD) and catalase (CAT), and decreased the content of malondialdehyde (MDA). Compared with CK1, 2 000 μmol·L^-1 SA decreased the ABA content by 79%, and increased the IAA and GA₁ contents by 32.2% and 2.66 times, respectively. In terms of gene expression, the expression levels of ABA synthesizing genes OsNCED2 and OsNCED3 were decreased by 94.26% and 90.24% compared with CK1 in seeds primed by 2 000 μmol·L^-1 SA, respectively, whereas the expression levels of ABA decomposing genes OsABA8’ox2 and OsABA8’ox3 were 5.9 and 3.9 times higher than that of CK1, respectively. Compared with CK1, SA priming significantly upregulated the expression of GA synthesizing genes OsCPS1, OsKAO and OsGA20ox1, while it significantly downregulated the expression of GA decomposing genes OsGA2ox2 and OsGA2ox6. In several candidate genes encoding cell wall relaxation protein, e.t. expansin, all but OsEXPB11 were significantly upregulated to some extent by priming. Compared with CK1, 2 000 μmol·L^-1 SA increased the expression levels of OsEXPA2, OsEXPB4 and OsEXPB6 to 12.2, 5.9 and 6.1 times, respectively.【Conclusion】SA priming can significantly alleviate the impact of low temperatures on rice seed germination and seedling growth, which is likely due to SA enhancing the activity of antioxidant enzymes such as SOD and CAT, reducing the production of MDA, and increasing the content of soluble sugars and proline, thereby strengthening the tolerance of seeds and seedlings to low temperatures. On the other hand, SA priming decreases endogenous ABA content, increases GA₁ content, enhances the activities of total amylase and β-amylase, and promotes the expression of genes related to cell wall relaxation, thus facilitating seed germination and seedling growth at low temperature.

【Background】In recent years, with the rapid development of remote sensing technology, real-time and non-destructive monitoring of crop growth status has become a research hotspot. Remote sensing-derived agricultural information will provide guidance for the precise management of large-scale crops. Among various remote sensing monitoring platforms, unmanned aerial vehicles (UAVs) have attracted wide attention due to their simple operation and low cost. UAVs equipped with multispectral cameras can quickly obtain crop growth conditions.【Objective】This study attempted to combine texture information and spectral information of multispectral images of fixed-wing UAVs to explore the monitoring effect of “atlas” information on rice growth indicators.【Method】A two-year rice field experiment involving different sowing dates, varieties, planting methods and nitrogen levels was conducted. During the key growth stages of rice, remote sensing images of the rice canopy were obtained using a Sequoia multispectral camera mounted on a fixed-wing UAV. Shoot destructive sampling was conducted simultaneously to obtain leaf area index (LAI), aboveground biomass (AGB), plant nitrogen content (PNC) and other agronomic indexes of rice. Simple regression, partial least squares regression and artificial neural network algorithms were used to construct rice growth index monitoring model based on multispectral images of fixed-wing UAV. The monitoring effects of spectral texture information in different models were compared and analyzed.【Result】The quantitative relationship between vegetation index (VI), single-band texture features and rice LAI, AGB, and PNC was explored using simple linear regression. The results showed that vegetation indexes had strong correlations with LAI and AGB, with the best-performing indexes being CIRE and NDRE, with R² values of 0.80 and 0.76, respectively. However, for PNC monitoring, vegetation indexes did not achieve ideal results, with the best-performing RESAVI and NDRE having R² values of only 0.13 with PNC. Further analysis using simple linear regression revealed that single-band texture features did not perform well in monitoring rice growth indicators. In order to further analyze the monitoring effect of image texture on the above three indexes, normalized texture indexes (NDTI), ratio texture indexes (RTI), and difference texture indexes (DTI) were constructed by referring to the construction method of VI. Correlation analysis showed that the newly constructed texture index (TI) improved the monitoring accuracy of rice growth indicators compared to single-band texture feature but did not perform better than vegetation indexes. To combine spectral and texture information, partial least squares and artificial neural network modeling methods were adopted in this paper. VI and VI+TI were used as different input parameter combinations to construct rice LAI, AGB and PNC monitoring models. The results showed that both partial least squares and artificial neural network modeling methods significantly improved the monitoring accuracy compared to simple linear regression. The best performance was achieved using VI+TI as input variables and an artificial neural network model for validation, with validation R² values for LAI, AGB, and PNC models increasing from 0.75, 0.72, and 0.26 to 0.86, 0.92, and 0.86, respectively, while RMSE values were significantly reduced.【Conclusion】The monitoring accuracy of rice LAI, AGB and PNC can be effectively improved by using the fixed-wing UAV to collect multispectral images of rice canopy and using the texture features and reflectance information as input parameters of the model through the model construction method of artificial neural network. The research results will provide a theoretical basis for rapid monitoring of large area crop growth.

In order to research the difference of Cd, Zn and As accumulation in different hybrid rice cultivars, 30 different hybrid rice cultivars were cultivated in a heavy metal and arsenic polluted paddy field which located in a mine zone of southern Hunan Province. The results showed that: there were certain differences of accumulation Cd, Zn and inorganic As between different genotypes of hybrid rice cultivars. The brown rice contents of Cd, Zn and As in 30 different hybrid rice cultivars were 0.28-0.83, 24.13-34.16, 0.45-0.77 mg/kg, respectively. Cd accumulation in brown rice of different genotypes of hybrid rice cultivars has significant difference, while Zn and As accumulation in brown rice is small differences. The significant difference of Cd content in brown rice exist between the two-lined hybrid rice and three-lined hybrid rice (P<0.05), and the differences of Zn and As contents in brown rice was not significant. Therefore, depending on differences of heavy metals accumulation in different hybrid rice cultivars, it indicated that the selection the pollution-safe cultivars were possible.

【Objective】The Pi9 resistance gene locus, conferring a broad-spectrum resistance against Magnaporthe oryzae, is consist by several tandem homologous genes. Over 10 resistance genes have been cloned from this gene locus. This study aims to clarify the R gene composition at Pi9 locus in rice resource materials and promote the application of those genes in rice resistance breeding.【Method】Comparing the DNA sequence of cloned R genes at Pi9 locus, the specific nucleotide polymorphism sites were screened as the candidate sites. Subsequently, each R gene was blasted with 155 rice genomes in the database of Rice Resource Center. The most specific nucleotide polymorphism sites were picked out from the candidate site in each gene to develop primer pair of molecular markers. The PCR product of primer pairs was used to mark indicated R gene in tested rice materials via parameter optimization. To verify the results, the R genes were cloned from indicated rice variety randomly and examined by Sanger sequencing, or analyzed the R genes from the genome database if the genome sequence of indicated rice variety exists in Rice Resource Center. The R genes in Pi9 locus have high homology, which cause same specific nucleotide polymorphism sites existing in different R genes. Therefore, some R genes are hardly identified by one molecular marker. For this case, several molecular markers were employed to identify the indicated R gene simultaneously. Moreover, some specific nucleotide polymorphism sites are single nucleotide polymorphism (SNP), in where the primers of molecular markers have a mismatched base. In order to improve the specificity of PCR amplification, the adjacent base of SNP was mutated to generate two mismatched bases at 3′ site of primer.【Result】Finally, the valid molecular markers were developed for each R gene and identified 32.09% tested materials containing R genes at Pi9 locus. Pi9, Pid4, PigmR, Piz-t, Pi2 and Pi9-type5 are present in 1, 7, 8, 14, 23 and 33 tested materials, respectively. The Pi9 only presents in monogenic line but not in rice parent lines. The other genes are usually present in two or more gene combinations in rice parent lines. The Pi9-type5 often presents in pair with Pi2 and Piz-t, and presents alone in three rice parents, Chenghui 993, HR2168 and Mianhui 365. Yuhui 38 contains the most R genes at Pi9 locus, including Pi2, Pi9-type5, PigmR and Pid4. Chuangu B, Chuannong 4B, Neixiang 6B and Shuang 1B contain Piz-t, PigmR and Pid4. Qianxiang 654B contains Piz-t and Pid4.【Conclusion】This study successfully developed specific molecular markers for six homologous rice blast resistance genes in Pi9 locus and identified the R gene composition in Pi9 locus for 110 rice parent lines that used in rice breeding in Sichuan basin. It also discovered different types of R genes combination at Pi9 locus and provided a clear reference for choosing the resistance source in rice breeding.

The root and photosynthesis physiological characteristics of different populations of two hybrid rice Honglianyou 6 and Liangyou 1193 after flowering stage under SRI were studied. Results showed that root density was higher in small population than those of lager population, but converse to the root activity. The chlorophyll contents of flag leaf were not different at flowering stage, but which was significantly higher than that of in low yield population, so the range of reduction per days was small in high yield population. The net photosynthesis rate of flag leaf in high yield population also was significantly higher than that of low yield population in reproductive stage. The yield superiority might result from its enhancement of physical activity of plant favorable to the grain development in reproductive stage

【Objective】 Rice yield is composed of effective panicle number per unit area, grains per panicle and grain weight, in which grain weight is mainly determined by grain morphology. Screening and identification of new grain type mutation materials and genes can lay a foundation for molecular design breeding of yield traits. 【Method】 A short and wide grain mutant short and widen grain1 (swg1) was identified in the mutant population of indica rice maintainer line Xida1B(XD1B) induced by ethyl methane sulfonate (EMS). The grain morphology and other agronomic characters were analyzed, and the glume was observed and analyzed by histocytology. Gene mapping was carried out by BSA method, and candidate genes were identified by genetic complementarity experiment. qRT-PCR was used to analyze the expression pattern of the gene and the expression level of other genes related to grain shape and cell development.【Result】 The analysis of agronomic characters showed that the grain length of swg1 mutant was significantly lower and the grain width was significantly higher than that of wild type, showing the phenotype of short and wide grains, and further histological and cytological analysis showed that the shortening of longitudinal cells of glume was the main reason for the shortening of grain length, while the increase of grain width was due to the increase of the number and size of transverse cells of glume at the same time. The results of genetic analysis showed that the mutation was controlled by a recessive single gene, and the candidate gene for SWG1 was determined to be LOC_Os07g42410 by map-based cloning and genetic complementary verification, which encoded a plant-specific transcription factor. qRT-PCR analysis showed that the expression of this gene had no obvious tissue specificity, and its expression is strong in stem, leaf and young panicle. According to the analysis of the expression of known genes related to grain shape, cell cycle and cell expansion, it was found that GS5 and GW8, which positively regulate the number and/or size of glume transverse cells to determine grain width, were significantly up-regulated in the mutants, while GW7/GL7 genes, which positively regulated the number and size of longitudinal cells and negatively regulated the number and size of transverse cells, were significantly down-regulated in the mutants. Some genes related to cell cycle and cell expansion also showed significant differences between mutants and wild types. 【Conclusion】 SWG1 encodes a plant-specific transcription factor, which affects glume cell proliferation and cell expansion by regulating grain shape genes GS5, GW8 and GW7/GL7, thus determining rice grain length and width.

【Objective】The F₁ hybrid sterility between XI/indica and GJ/japonica severely hinders the utilization of hybrid advantage between subspecies. Exploring the genetic mechanism and identifying new regulatory genes for XI/GJ hybrid sterility will provide theoretical basis for promoting genetic improvement of XI/GJ hybrid seed setting rate. 【Method】A series of stable genetic recombination inbred lines (RILs) containing 95 plant lines were derived from the cross between XI variety Habataki and GJ variety Sasanishiki after 10 generations inbred using single seed descent method. High throughput sequencing was performed on both parents and RILs on the Illumina platform, and the distribution of Habataki pedigree in RILs was analyzed at the whole genome level. The segregation distortion regions were identified, and hybrid sterile related gene loci were screened within the segregation distortion regions, then identified candidate genes through sequence alignment comparison. The targeted gene was knockout to verify the function using CRISPR gene editing technology. 【Result】The hybrid F₁ plants derived from the cross between Habataki and Sasanishiki showed significant heterosis in panicles, grains per panicle, and thousand grain weight, but its seed setting rate significantly decreased. I₂-KI microscopy revealed a significant decrease in F₁ pollen fertility. High throughput sequencing of the entire genome of RILs revealed significant segregation distortion on Chr.1, Chr.3, Chr.5, Chr.6, Chr.7, and Chr.12, indicating that the genotype in this region tends towards the Habataki. Sequence alignment comparison revealed that Sc, S5, and HSA1 are target genes for the segregation distortion on Chr.3, Chr.6, and Chr.12. The CRISPR gene editing mutants with a knock-out Sc-Haba-3 allele in Habataki successfully improved the pollen fertility and seed setting rate of F₁ hybrid with Sasanishiki. A complex structural variation was found between Sasanishiki and Habataki in the segregation distortion of Chr.1. A 24.7 kb segment containing 4 predicted genes in the Sasanishiki genome was replaced by a 64.8 kb segment containing 10 predicted genes in Habataki, the structural variation may involve in controlling the hybrid sterility of XI and GJ cross. 【Conclusion】This study detected multiple XI/GJ hybrid infertility related loci, and successfully improved F₁ fertility by using CRISPR gene editing to knock out multiple copies of Sc in Habataki, locking in the target gene in the Sd region of Chr.1.

In this paper, the research status and development trend of rice quality at home and abroad were reviewed, the genetic basis of rice quality formation, regulatory molecular mechanisms and strategies for optimizing rice quality were summarized, and the correlation between rice quality and related genes such as starch, protein, lipid, aroma and color was revealed. Two specific countermeasures to improve rice quality, gene editing technology and molecular marker-assisted technology, were described. The challenges in rice quality research, such as imbalance between rice quality and yield, difficulty in transforming and popularizing rice quality improvement technology, regional adaptability of rice in breeding process, high breeding cost and long breeding cycle, and consumer acceptance of improved rice, were pointed out. Countermeasures were put forward from the aspects of multi-party cooperation and resource sharing, strengthening basic research and innovative technology, efficient screening and evaluation methods, considering diversified needs, and promoting the integration of industry-university-research and technology transformation, so as to provide theoretical guidance for optimizing rice quality and cultivating high-quality rice varieties.

Yu Yahui, Xu Zhengjin

The storability of rice seeds is an important trait related to grain storage safety and the safety of seed use, it is also the focus in seed research and by seed enterprises. Rice seeds with strong storability still exhibit high seed vigor after long-term storage, these rice varieties can be better used to solve the problem of grain storage and the safety of seed use. In this review, we introduced the reasons of seed aging and deterioration, discussed the physiological and biochemical mechanisms of seed during storage, summarized the research progresses of genetic mechanism of rice seed storability. Finally, we made an outlook for how to breed the new variety of rice with strong storability.

【Objective】 Rice is an important food crop, providing staple food for more than half of the world’s population. Panicle traits are the main factors affecting rice yield. Discover the elite haplotype of the panicle regulation gene, and provide important germplasm and gene resources for pyramiding breeding. 【Method】 In this study, recombinant inbred lines (RILs) derived from a cross between SN265 and R99 were re-sequenced through high-throughput sequencing. QTL analysis and candidate gene identification were conducted on the grain number on the primary branch, the grain number on the secondary branch, and the grain shape. The sequences of candidate genes were compared using the long-read sequence assemblies of SN265 and R99. The combination of candidate genes that can maximize grain yield was selected among RILs. Finally, the super rice variety SN265 was improved using CRISPR/Cas9 gene editing technology. 【Result】 The R99 had significantly more grain number per panicle and grain number on the secondary branch, whereas SN265 had significantly more grain number on the primary branch. The grain of R99 is slender, and the grain of SN265 is short and round. The RILs were sequenced with approximately 6.25-fold depth. For parent lines, 30.0-fold depth and 32.0-fold depth data were generated for R99 and SN265, respectively. Subsequently, a bin map was constructed by 1456445 high-quality SNPs. The genetic map containing 3 569 recombinant blocks, with an average length of 58.17 kb. The QTL analysis detected a QTL on Chr.9 for grain number per panicle and grain number on both primary and secondary branch, a QTL on Chr.1 for grain number per panicle and grain number on the secondary branch, a QTL on Chr.5 for grain shape. The candidate gene prediction and sequence comparison showed that DEP1 regulated the grain number on both primary and secondary branches of rice, Gn1a mainly regulated the grain number on secondary branches of rice, and qSW5 mainly regulated the grain shape. The yield of the combination of Gn1a^R99/DEP1^SN265/qSW5^SN265 alleles showed an advantage in yield performance among the RILs. We further conducted a molecular design breeding to SN265 by knocking out the Gn1a locus using CRISPR/Ca9 gene editing technology, and the grain number per panicle of the transgenic plants increased significantly compared to that of SN265. 【Conclusion】 This study used RILs derived from a XI/GJ cross and high-throughput sequencing technology to conduct QTL analysis of rice panicle traits, revealed the effects of DEP1, Gn1a, and qSW5 on grain number per panicle and grain shape, and clarified that Gn1a^SN265/ DEP1^R99/qSW5^R99 was the best gene combination in RILs. The yield per plant was further improved by knocking out the Gn1a locus of SN265. This study provided important germplasm and gene resources for pyramiding breeding with elite alleles.

Rice root bleeding sap can act as the research base of rice root activity and the diagnosis of nutritional status. There is close relationship between the bleeding sap and rice aboveground and yield. The conception of rice bleeding sap, composition ingredients, root bleeding intensity variation, influential factor and its relationship with aboveground are reviewed in this paper. Some suggestions on the rice bleeding sap including collection methods are also pointed out.

To explore the growth differences among different green manure varieties and their effects on rice yield, nutrient accumulation and soil properties after turning over, the winter fallow field (CK) was used as the control, three common green manures (Astragalus sinicus L., Vicia villosa var. and Vicia sativa L.) were selected to conduct field experiments to analyze the differences in the characteristics of green manures during the growth period and their effects on rice yield, nutrient accumulation and soil properties after turning over. The results showed that the performance of plant height and biomass in the three types of green manure was as followed: Vicia villosa var. > Vicia sativa L. > Astragalus sinicus L., with Vicia villosa var. being the best and suitable for planting in the region. After turning over green manures, the rice yield significantly increased compared to CK, with the yield under Vicia villosa var. reached 10.47 t/hm², which was 58.88% higher than that of CK. Green manure turning over could improve the taste value and nutrient accumulation of rice. Compared with CK, the taste value of rice treated with Astragalus sinicus L., Vicia villosa var. and Vicia sativa L. increased by 5.58%, 9.46% and 11.16%, respectively, and total potassium accumulation in rice straw increased by 50.88%, 42.87% and 67.70%, respectively, the total nitrogen accumulation in rice grains increased by 17.25%, 45.62% and 47.74%, respectively and the total potassium accumulation in rice seeds increased by 17.96%, 54.28%, and 48.88%, respectively, the total phosphorus accumulation in rice shoots increased by 11.32%, 62.16% and 27.41%, respectively, the total accumulation of total potassium increased by 45.53%, 44.73% and 64.64%, respectively, with the best comprehensive effect being the Vicia villosa var. and Vicia sativa L.. Green manure could improve soil properties and had the potential to improve soil fertility. Among them, the treatment of Vicia sativa L. had a pH increase of 2.96%, organic matter increased by 10.05%, and total nitrogen content increased by 4.41% compared to CK. The treatment of Astragalus sinicus L. had an organic matter increase of 1.43%, total nitrogen content increase of 24.25%, total phosphorus content increase of 9.20%, and available phosphorus content increase of 10.95% compared to CK. In summary, the biomass and nutrient accumulation of Vicia villosa var. and Vicia sativa L. were both high, and their flipping could improve the yield, taste value and nutrient accumulation of rice. Therefore, they were recommended as green manure varieties for planting in this region; Astragalus sinicus L. and Vicia sativa L. had the potential to increase soil fertility through tillage, while Vicia sativa L. had a better effect. This study could provide a theoretical basis for the utilization of green manure and sustainable agricultural production in the northern Jiangsu region.

High-temperature stress is a major constraint to higher and stable productivity and super quality of rice, there is of great theoretical and practical significance in investigating heat tolerance in rice. Achievements up to now that are related is elaborated,including:1.the impact of high temperature on the growth and development, yield and grain quality, the physiological or biochemical processes; and 2. the performance of heat tolerance. Additionally, some suggestion about heat-tolerance breeding are given.

The global warming rate and the frequency of extreme high temperature weather are continuously increasing, which could bring catastrophic impacts to rice production. To further clarify the response mechanism of rice to high temperature, this article summarized the research progress in the direction of rice heat damage from high temperature, focused on the impact of high temperature on rice production, and deeply analyzed the physiological (photosynthetic characteristics/antioxidant system) and gene molecular mechanisms of rice’s response to high temperature. We concluded that the heat tolerance characteristics of rice were formed by the interaction between varieties and the environment. Results showed that, the photosynthetic characteristics of rice were influenced by both stomatal and non-stomatal limiting factors, and the antioxidant process was achieved by enhancing the activity of antioxidant enzymes and reducing the content of malondialdehyde; rice improved plant heat adaptability by activating the expression of key genes and stimulating the transduction of heat signals within the plant; by optimizing “Before production-During production-After production” comprehensive management and monitoring system, we could explore innovative cultivation systems, and thoroughly investigate the high temperature defense mechanisms of rice. Therefore, this study aimed to clarify the physiological and molecular mechanisms of rice in response to high temperature stress, providing a scientific reference for future heat-tolerant rice breeding work and improving rice sustainable production.

Since the transgenic technology of pollen tube pathway method was formally established, it has been widely used in crop genetic improvement. Extensive research shows: compared with other Transgenic technologies, the transgenic technology of pollen tube pathway method has the advantages of transform seeds can be directly got, high transform frequency, easy and simple to handle, The properties are steady, material variety, etc. This paper introduced the principle of transgenic technique by pollen tube pathway. This method is used to channel plants DNA into rice and variation like plant form, output properties, Disease-resistance, rice quality and Physiological biochemistry, etc. It is a easy and effective rice molecular breeding.

【Objective】The twin-screw extrusion process was used to produce extruded rice products with P. eryngii powder and rice flour as raw materials, and the predicted glycemic index of the products was analyzed to provide technical support for the development of edible mushroom extruded rice products with comprehensive nutrition and low glycemic index. 【Method】 The content of protein, crude fiber, amino acid and fat of extruded rice with 20%, 40% and 60% P. eryngii powder were determined. RVA rapid viscosity analyzer and rotary rheometer were used to analyze the gelatinization properties and rheological properties of P. eryngii powder with different additive amounts. The internal structure, color, texture properties, starch hydrolysis rate, predicted glycemic index (pGI) and sensory score of extrusion-rice with different dosage of P. eryngii were analyzed by scanning electron microscopy, colorimeter, texture analyzer, and in vitro digestion and sensory evaluation. 【Result】Compared with blank extruded rice, the content of protein, crude fiber and amino acid in extruded rice was significantly increased by adding P. eryngii powder, and the content of protein was increased by 71.84%, 70.19% and 96.70%, and the content of crude fiber was increased by 14.22%, 28.88% and 49.81%, respectively. The total amino acid content increased by 40.98%, 58.96% and 66.03%, respectively. The gelatinization and rheological properties of the mixed powder system showed a decreasing trend with the increase of the added amount of P. eryngii powder, and the peak viscosity, valley viscosity, final viscosity, disintegration value and recovery value gradually decreased, and G'and G" gradually decreased. The typical weak gel accounted for a large proportion of elasticity, and the added amount of 20% P. eryngii powder was the closest to the powder parameters of rice flour. Compared with the blank extruded rice, it was found by scanning electron microscopy that the cross section pores of extruded rice increased with the increase of the powder content, and the structure tightness decreased. Among them, 20% of extruded rice had tight structure and less cracks. The values of L^* and b^* in extruded rice of P. eryngii by colorimeter decreased significantly, and a^* increased first and then decreased. The water absorption rate and cooking loss rate after cooking increased with the addition of P. eryngii powder, but the expansion rate had no significant effect, and the cooking characteristics of 20% P. eryngii extruded rice were the best. The hardness, elasticity, adhesiveness and chewability of the extruded rice increased with the addition of P. eryngii powder, while the cohesiveness and resilience first decreased and then increased. Starch digestibility, rapidly digestible starch (RDS), slowly digestible starch (SDS) and predicted glycemic index (pGI) also increased with the increase of P. eryngii powder addition, but they were all lower than that of normal rice and blank extruded rice, while resistant starch (RS) content was greater than that of the two groups and increased with the increase. The predicted glycemic index (pGI) value of 20% P. eryngii extruded rice was the lowest 60.18, which was 20.60 lower than that of normal rice, and the content of resistant starch (RS) was the highest. Sensory evaluation showed that the appearance structure, palatability, taste, cold rice texture and comprehensive score of P. eryngii extruded rice decreased with the increase of the amount of P. eryngii powder, while the odor score decreased first and then increased. From the point of view of the score, 20% of P. eryngii extruded rice was 66.75 scores, which was the most acceptable to consumers. 【Conclusion】 20% of extruded rice with P. eryngii was nutrient-rich and had suitable texture indexes. The predicted glycemic index (pGI) was 60.18, which was 20.60 lower than that of normal rice. The nutritional value of extruded rice was significantly improved by adding P. eryngii powder, and the food quality was better.

【Objective】FWL (Fruit Weight2.2-Like) gene is a negative regulator of cell proliferation, which not only regulates plant organogenesis and organ size, but also participates in the regulation of metal ion transport accumulation and signal transduction. Analyzing of the function of OsFWL3 gene is helpful to reveal the transport mechanism of trace metal elements in crops. It provides theoretical support for reducing heavy metal accumulation and improving crop quality. 【Method】The gene information, genome structure and phylogenetic tree of OsFWLs family were analyzed by bioinformatics method, and the expression profile of OsFWL3 gene was predicted. Two OsFWL3 knockout lines were obtained using CRISPR/Cas9 gene editing technology. Then wild type and Osfwl3 mutants were treated with ZnSO₄ at seedling stage and filling stage, respectively. The phenotypes of plants and grains after treatment were analyzed, and the content variation of metal elements such as Zn was determined to explore the effects of OsFWL3 on the transport and accumulation of metal ions and seed quality. 【Result】The gene function of OsFWLs family is similar to some extent. OsFWL3 gene is highly expressed in anther and panicle, indicating that it is closely related to reproductive development of rice. The number of primary branches, grian length, grain thickness and 100-grain weight of Osfwl3 mutants are significantly larger than WT. OsFWL3 affects the content and distribution of Zn and other metal ions in rice seedlings and grains. The deletion of OsFWL3 gene affects the competitive transport of Zn, Cd and Mn from underground to above-ground, lower grain to central grain and husk to brown rice. 【Conclusion】OsFWL3 gene affects the distribution of Zn and other metal ions in rice grains and plants, and it plays an important role in regulating the growth and development of rice plants and grain size.

Licorice is a common traditional Chinese herbal medicine and its chemical constituents, pharmacology and utilization have been widespread concerned. The research progress on the resource distribution, chemical constituents and their extraction and separation methods, pharmacological effects, development and utilization of licorice are reviewed, which would provide theoretical and methodological bases for further development and utilization of licorice resources.

Phosphorus (Pi) is one of the major nutrients for higher plant growth and development, Recently studies show that plant phosphate transporters mediate the uptake and translocation of this nutrient within plants. Under conditions of Pi starvation, the major mechanism for Pi uptake by roots is usually considered to be the high affinity system. And the majority of the plant PTs belong to the Pht1 family. In this paper, the research progresses of rice phosephate transporters Pht1 on expression regulation and biological properties in last decade were reviewed.

Eleven rice cultivars and three different seed soaking time (24h, 120h and 168h) were used to investigate the effect of different seed soaking time on germinative energy and germinative percentage of rice seed. The results showed that there were significant difference in germinative energy and germinative percentage of different rice cultivars, seed soaking time had no significant effect on germinative energy but had significant effect on germinative percentage of rice seed, and it was disadvantaged to seed germinate that seed soaking time was too short or long. Seed soaking for 5d was advantage for germinates in this study.