【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.
【Objective】Genetic improvement for efficient utilization of maize nutrients represents a crucial method to ensure national food security. Exploring quantitative trait locus (QTL) and related candidate genes of nitrogen use efficiency can provide a theoretical basis for improving the efficiency of nitrogen fertilizer in maize and cultivating high-yield and high-efficiency maize varieties. 【Method】In this study, QTL mapping analysis in one recombinant inbred line (RIL) population constructed by KA105 and KB024 was performed for grain yield under two different nitrogen treatments, including the derived traits partial factor productivity from applied nitrogen (PFPN), low nitrogen tolerance coefficient (LNTC) and nitrogen agronomic efficiency (NAE). Concurrently, integrating the seedling transcriptome data of the parent KA105 under nitrogen treatment, differentially expressed genes were identified, and candidate genes associated with maize nitrogen use efficiency were mined through co-expression analysis. Subsequently, the selected candidate genes were validated using qRT-PCR. 【Result】Through mapping analysis, a total of 36 QTLs distributed across different chromosomes were detected, explaining 1.63% to 17.26% of the phenotypic variation. Among these, eight major QTLs with a phenotypic variation explanation rate exceeding 10% were identified, along with seven genetically stable QTLs commonly identified across different traits or environments. Notably, qNNGYP1 located on chromosome 1 has been repeatedly detected in previous studies, with a phenotypic explanation rate of up to 11.73%. Additionally, other QTLs (qNNGYP1, qPFPN1) co-located in this interval across different environments, suggesting it as a focal region for further investigation. Combining transcriptome data of seedlings under low nitrogen stress, 39 differentially expressed genes within these QTL intervals were identified, and 6 key genes were identified through co-expression network prediction. The result of qRT-PCR indicated that the expression trends of the candidate genes under both nitrogen treatments were consistent with the transcriptome data. Specifically, GRMZM2G366873 was involved in the regulation of auxin homeostasis and may participate in maize responses to low nitrogen stress, drought stress, and boron stress through auxin signal transduction, also regulating ear length. GRMZM2G414192 was involved in the response of the photosynthetic system to low nitrogen stress and was regulated by brassinosteroids. GRMZM2G414043 was associated with maize grain length and biomass, while GRMZM2G040642 may be involved in the long-distance signal transduction of nitrogen. 【Conclusion】In summary, a total of 36 QTLs were identified, distributed across chromosomes 1, 4, 5, 7, 8, and 9, including eight major QTLs (PVE>10%). The candidate genes GRMZM2G366873, GRMZM2G414192, GRMZM2G414043, and GRMZM2G040642 were identified as potential genes for maize nitrogen efficiency.
【Objective】At present, Kunlun 14 and Kunlun 15 are the main varieties of the naked barley in Qinghai Province, and also the important backbone parents in the breeding of the naked barley. The genomic sequences of Kunlun 14 and Kunlun 15 were compared to provide references for the trace of important character regions/loci, pedigree analysis and their utilization in molecular design breeding of the naked barley. 【Method】In this study, the agronomic and grain traits of Kunlun 14 and Kunlun 15 were investigated in the field, and the whole genome resequencing were performed (sequencing depth ≥15×). The sequence differences of copy number variation (CNV), single nucleotide polymorphism (SNP) and insertion/deletion (InDel) were compared between the two varieties. According to the SNP distribution patterns, the polymorphism hotspot and genetic similar regions between them were identified. The mutation types of polymorphism hotspot and genetic similar regions were compared and analyzed. The gene enrichment analysis was carried out in the specific CNV regions and the polymorphism hotspots regions of the two varieties. 【Result】In addition to the plant height and peduncle internode length, Kunlun 14 and Kunlun 15 had high similarity in important agronomic and grain traits. Compared with the barley reference genome of Morex, the two varieties had a common CNV variation interval of 83 Mb, and the length of cultivar-specific CNV variation interval in Kunlun 14 and Kunlun 15 was 37 Mb and 38 Mb, respectively. There were 564 genes in the CNV region specific to Kunlun 14, which were significantly enriched in 15 GO terms, while 519 genes were in the CNV region specific to Kunlun 15 and were significantly enriched in 7 GO terms. Based on the SNP distribution patterns, 1 706 Mb polymorphism hotspots and 2 411 Mb sequence similarity intervals of Kunlun 14 and Kunlun 15 were identified at the whole genome level, and the polymorphism hotspots were mainly distributed on 3H, 6H and 7H. The polymorphism hotspots regions contained 16 768 genes, whose functions were mainly related to plant growth and development. There was no significant difference between polymorphism hotspot regions and genetic similar regions in SNP variation type, InDel length distribution and the proportion of mutations affecting coding function. The SNPs and InDel mutations in polymorphism hotspot and genetic similar regions were mainly missense mutations and followed by synonymy mutations. 【Conclusion】The field phenotypes of Kunlun 14 and Kunlun 15 were similar. At the whole genome level, a total of 75 Mb CNV variation regions between them and the polymorphism hotspot regions were mainly distributed at 3H, 6H and 7H.
【Objective】This study aimed to explore the underlying reasons for the reduction of maize photosynthesis under the high temperature and drought combined stress, so as to provide theoretical basis for alleviating the combined stress of high temperature and drought. 【Method】Maize cultivar “Denghai 605” was selected as the experimental material for this experiment. Two temperature levels were set, namely normal temperature control (30 ℃/22 ℃ for day (8:00-18:00)/ night (18:00- 8:00 the next day)) and high temperature treatment (38 ℃/28 ℃ for day/night). The two water conditions were normal water supply control (soil water content was 70%-80% of field capacity) and drought treatment (soil water content was set to 50%-60% of field capacity). There were four treatments in the experiment, including control (CK), high temperature stress (H), drought stress (D), high temperature and drought combined stress (HD), and the treatment began at VT stage (VT). The changes in leaf gas exchange parameters, photosystem Ⅱ (PSII) performance, key photosynthetic enzyme activity, plant biomass, and grain yield under different stress treatments were analyzed. 【Result】High temperature, drought and combined stress all led to the increase of chlorophyll fluorescence parameters, the ratio of a variable fluorescence FK to F0-FJ amplitude (WK) and variable fluorescence FJ to F0-FJ amplitude (VJ), and damaged the donor side and acceptor side of PSII. Compared with the control, PSII maximum quantum yield for primary photochemistry (φP0), the probability of captured excitons transferring electrons to other electron acceptors in the electron transfer chain beyond QA (Ψ0), quantum yield for electron transport (φE0), quantum yield of energy dissipation (φD0), quantum yield for reduction of the end electron acceptors at the PSI acceptor side (φR0), and performance index based on absorption of light energy (PIABS) were significantly decreased, and the absorption and transfer of light energy were inhibited; absorbed photon flux per active PSII (ABS/RC), trapped energy flux per active PSII (TR0/RC) and dissipated energy flux per active PSII (DI0/RC) increased significantly, but the electron flux from QA‒ to the PQ pool per active PSII (ET0/RC) decreased significantly, which affected the energy distribution of reaction centers, reduced the number of PSII active reaction centers, and inhibited the performance of PSII. Combined stress could aggravate the inhibition of PSII performance by damaging the donor side, the acceptor side and the active reaction center. At the same time, the activities of ribose 1, 5-diphosphate carboxylase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) decreased, which inhibited photosynthetic carbon assimilation. High temperature, drought, and combined stress reduced the net photosynthetic rate by reducing the performance of PSII and the activity of key photosynthetic enzymes. Compared with the control, the net photosynthetic rate of VT+5 d was reduced by 14.6%, 31.4%, and 39.9%, respectively. The decrease in photosynthetic rate inhibited the accumulation of biomass and its transport to grains. Under high temperature, drought, and combined stress, the grain yield decreased by 80.3%, 27.1%, and 84.0% than that under control, respectively. 【Conclusion】In summary, the combined stress of high temperature and drought mainly reduced net photosynthetic rate, hindered biomass, and reduced grain yield by inhibiting leaf PSII performance. The impact of combined stress on PSII performance and grain yield was greater than that of single stress under high temperature and drought.
【Objective】Reasonably increasing planting density combined with appropriate nitrogen (N) application rate is an important technical approach for increasing maize yield and resource use efficiency. Understanding the interactive effects of planting density and N rate on maize growth, evapotranspiration (ET) and water use efficiency (WUE) during the growing season, could provide a basis for improving its use efficiency when increasing planting density and controlling N input in maize production. 【Method】Field experiments were conducted during 2022 to 2023 in Jilin Province. Two maize cultivars, Liangyu 99 (LY99) and Demeiya 3 (DMY3), were used in this study. Three planting densities of 50 000, 70 000 and 90 000 plants/hm2 and four N application rates of 0, 100, 200 and 300 kg N·hm-2 were designed to investigate the effects of planting density and N application rate on grain yield and water productivity of different maize cultivars, as well as the dry matter (DM), soil water content, ET and WUE at various growth stages. 【Result】Planting density significantly affected DM and grain yield of maize, but the response trends varied between cultivars. Grain yields of LY99 with 70 000 plants/hm2 was 11.1% and 18.3% higher than that with 50 000 and 90 000 plants/hm2, respectively. The average yield of DMY3 planted with 70 000 plants/hm2 and 90 000 plants/hm2 was 10.5% and 9.3% higher than that of 50 000 plants/hm2, respectively. Nitrogen fertilization significantly increased DM and grain yield of maize, and also showed significant interactive effects with cultivar or planting density. Compared with N0, grain yields of LY99 were increased by 38.0% to 60.7% under N1, and the yield increases for DMY3 were 24.4% to 38.2%. Notably, the yield responses to N rates were more pronounced for LY99 compared with DMY3. For both cultivars, the yield differences between low N rate and high N rate enlarged with increasing planting density, with LY99 showing a more distinct performance. The water consumption and utilization of maize plants were also significantly affected by planting density, N rate and their interaction. During the growing season, the total ET of DMY3 continually increased with increasing density, while that of LY99 showed the highest values with 70 000 plants/hm2 among different densities. In each density condition, the ET of both cultivars increased with increasing N application rates. The WUE of maize plants showed complex responses to planting density and N rate at different growth stages, due to the varied annual precipitation and distribution patterns. The average increase of water productivity of LY99 under planting 50 000 and 70 000 plants/hm2 was 8.6% and 10.4% compared with 90 000 plants/hm2 respectively. DMY3 had the highest water productivity when planting 70 000 plants/hm2, which increased by 5.8% and 5.3% compared with 50 000 and 90 000 plants/hm2, respectively. The water productivity showed different responses to N rate among the three densities. In general, the difference of nitrogen application under low density was small, but it increased significantly under medium and high density. Compared wtih DMY3, LY99 showed higher increases for water productivity when N fertilizer was applied under medium and high density conditions. The correlation analysis showed that interactive effects of planting density and N rate significantly affected maize yield and water productivity by influencing the water utilization at various growth stages. 【Conclusion】Planting density and N rate had significant interactive effects on maize yield and water utilization in the rain-fed region of Northeast China. The two maize cultivars used in this study could obtain high grain yield and water productivity under a moderately higher density of 70 000 plants/hm2 combined with 200 kg N·hm-2 rate.
【Background】Grey mould, caused by Botrytis cinerea, poses serious threats to tomato production. Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) from plant is involved in the regulation of responses to biotic and abiotic stresses. However, whether tomato SnRK1 is involved in tomato resistance to grey mould remains unclear. 【Objective】In this study, SlSnRK1.2, which was up-regulated in the process of B. cinerea infecting tomato, was used as the research object to clone and analyze its function of regulating grey mould resistance, so as to provide theoretical basis and gene resources for the prevention and control of tomato grey mould. 【Method】The expression patterns of SlSnRK1.2 during the infection stage of B. cinerea and in different tomato tissues were examined through real-time fluorescence quantitative PCR (qRT-PCR); Subcellular localization of SlSnRK1.2 was analyzed using Agrobacterium-mediated transient transformation system; SlSnRK1.2 silencing plants were constructed by tobacco rattle virus (TRV)-mediated gene silencing (VIGS) technology, and the role of SlSnRK1.2 in the interaction between tomato and B. cinerea was preliminarily analyzed. The overexpression plants of SlSnRK1.2 were created by Agrobacterium-mediated tomato genetic transformation system, and the role of SlSnRK1.2 in regulating tomato resistance to grey mould was further clarified. NbSnRK1.2, a homologous gene of SlSnRK1.2, was silenced in N. benthamiana using TRV-mediated gene silencing technology to determine the function of NbSnRK1.2 during the interaction between N. benthamiana and B. cinerea. 【Result】Micro-Tom was used as the wild-type (WT) background, qRT-PCR technology was used to clarify that the transcriptional expression of SlSnRK1.2 was significantly induced by B. cinerea infection. Subcellular localization analysis revealed that SlSnRK1.2 was localized in the cytoplasm and nucleus. qRT-PCR analysis showed that SlSnRK1.2 was expressed in roots, stems, young leaves, mature leaves, flower buds, and flowers of tomato, with the highest relative expression level in the stems. Transient silencing of SlSnRK1.2 attenuated tomato resistance to grey mould, while overexpression of SlSnRK1.2 enhanced tomato resistance to grey mould. On this basis, transient silencing of NbSnRK1.2, a SlSnRK1.2 homologous gene, attenuated tobacco resistance to grey mould. 【Conclusion】SlSnRK1.2 positively regulates tomato resistance to grey mould and can be used as a genetic resource for molecular breeding of tomato resistance to grey mould.
