The rapidly evolving genome editing technologies have demonstrated strong application potential in animal and plant breeding, microbial engineering, and basic scientific research. Current genome editing techniques allow for the insertion, deletion, and substitution of single or multiple nucleotides at specific genomic targets across a wide range of species. However, editing types involving large DNA fragment insertion or replacement still face technical bottlenecks, such as low efficiency and fidelity, as well as difficulties in donor delivery. These limitations restrict the application of gene editing in important scenarios, including multigene stacking with genetic linkage, precise replacement of favorable alleles, and targeted integration of DNA fragments at genomic safe harbors. Transposable elements, as mobile genetic elements widely present in biological genomes, offer a novel approach to overcoming these challenges due to their inherent mobility and large DNA cargo capacity. They hold promise for being engineered into key molecular tools for precise large DNA fragment editing. This review summarizes recent advances in targeted large DNA fragment insertion technologies based on transposable elements, focusing on the application status and prospects of prokaryotic-derived CRISPR-associated transposons (CAST) and certain DNA transposons and retrotransposons in eukaryotes. Prokaryotic-derived CAST systems have shown outstanding performance, enabling efficient large fragment integration in prokaryotes and, after optimization, also achieving large fragment insertion in eukaryotic cells. In eukaryotes, engineered DNA transposons such as mPing/Pong and retrotransposon-related tools like R2 and L1 have been utilized for large DNA fragment insertion in animals and plants. At the same time, the field of transposon-based large DNA fragment insertion faces challenges. On the one hand, the cross-species adaptability of transposable elements is limited, making it difficult for some elements to function when transferred to other species. On the other hand, the large size or multiplicity of protein components involved leads to low delivery efficiency in certain types of eukaryotic cells. Additionally, some systems carry safety risks, such as stimulating the mammalian immune system and triggering inflammatory responses. Future research may focus on the discovery of novel transposable elements, engineering of transposases, development of new delivery vectors, and in-depth elucidation of transposition mechanisms, in order to provide key technical support for establishing efficient and safe large fragment editing technologies. This will contribute to foundational innovations in crop genetic improvement, gene therapy, and microbial genome editing.
【Objective】Salt stress limits the stable and increased yields of faba beans (Vicia faba L.) on saline-alkali soils. This study aims to improve the efficiency and accuracy of distinguishing salt tolerance differences among various materials at early stages by combining indoor germination assays with field observations. Additionally, it evaluates the potential of exogenous itaconic acid (IA) at different doses and acidic treatments to alleviate salt stress during the germination stage, providing complementary pathways for early prediction and exogenous regulation. 【Method】 Fifteen faba bean germplasm materials were selected for germination tests under 100 mmol·L-1 NaCl conditions. Various indices, including relative germination rate (RGR), relative germination energy (RGE), relative root length (RRL), vigor index (VI), germination index (GI), and germination stress index (GSI), were measured. Comprehensive evaluation and classification were performed using the comprehensive membership value μ(Xi). Field trials were conducted on both saline-alkali and non-saline-alkali soils, tracking seedling emergence rate, Soil and Plant Analyzer Development (SPAD) values at the bud stage, flowering-stage salt injury index (SI), and 17 agronomic traits to form a field classification of salt tolerance. Stratified 5-fold cross-validation was employed to assess the performance of field-grade determination, using F1 metrics. For the IA treatment, three representative germplasms were selected, and a gradient of 0% to 1% IA was applied under 100 mmol·L-1 NaCl. Acetic acid (CH3COOH) and pH7.0 treatments served as controls to analyze the alleviating effects of IA on salt stress. 【Result】Significant differences were observed in all indices among the different classifications at the germination stage, showing strong discriminatory power across materials, with comprehensive scores showing a continuous gradient from salt-sensitive to salt-tolerant materials, allowing for classification. Field observations indicated that seedling emergence rates and SPAD values decreased in most materials under saline-alkali conditions, although some materials still performed well. Overall, germination-stage classification correlated well with field classification, with approximately 73% of materials showing consistency across both stages, suggesting that germination assessments are indicative of actual field salt tolerance. A supervised model built on key germination-stage traits (VI, RGE, RGR, and GSI) showed a moderate ability to predict field classification, achieving F1=0.50, Precision=0.46, and Recall=0.60 under stratified 5-fold cross-validation, providing quantitative support for early-stage screening of salt-tolerant germplasm. Low doses of IA (e.g., 0.01%) improved the germination vigor and root growth of the materials, but no similar effect was observed with equimolar acetic acid. When the external solution was adjusted to pH 7.0, the promoting effect of IA significantly weakened or disappeared, indicating that its alleviating effect is not only related to molecular structure but also closely associated with a weak acidic environment. Additionally, the effect exhibited variety-specific responses, with germplasm V434 showing higher responsiveness. 【Conclusion】 The combined evaluation of indoor germination assays and field observations effectively distinguishes salt tolerance differences among faba bean materials at early stages. Indices such as vigor index (VI), germination stress index (GSI), and relative germination rate (RGR) effectively reflect field-grade performance and improve initial screening efficiency. IA demonstrates a dose-dependent, pH-sensitive alleviating effect during germination; however, its stability and applicability need further validation under complex saline-alkali stress and field conditions.
【Objective】Aiming at the problems of low photosynthetic performance and yield decline of maize leaves caused by large amount of plastic input and extreme high temperature in traditional maize planting in oasis irrigation area, the photosynthetic physiological mechanism of maize during grain filling period under two years of plastic mulching was studied, so as to provide the theoretical basis for the construction of high grain yield technology of plastic reduction in oasis irrigation area. 【Method】In 2013, a randomized block experiment was conducted in the oasis irrigation area of the Hexi Corridor. According to the duration of plastic mulching, three treatments were formed: no-tillage with plastic re-mulching and using (NTP), no-tillage in autumn and plastic mulching in spring (RTP), and conventional tillage with annual new plastic mulching (CTP, as the control). The response of chlorophyll content, gas exchange parameters, key enzyme activities of photosynthetic physiology, relative gene expression and key protein content of maize leaves to different plastic utilization methods was explored. 【Result】Different plastic utilization methods promoted the increase and stability of maize yield by regulating the photosynthetic physiological characteristics of maize filling stage. Compared with CTP, chlorophyll a and b in NTP filling stage increased by 15.1% and 8.3% on average, respectively, indicating that NTP treatment was beneficial to maintain the chlorophyll content of maize, thus effectively delaying the degradation of chlorophyll and promoting the photosynthesis of maize. Compared with CTP treatment, the net photosynthetic rate and transpiration rate under NTP increased by 25.2% and 11.5%, 20.0% and 12.2%, respectively, in the middle and late stages of grain filling, indicating that NTP treatment was beneficial to regulate the gas exchange parameters of maize during grain filling stage and enhanced the photosynthesis of maize during grain filling stage. At the same time, NTP maintained higher photosynthetic physiological key enzyme activity, relative gene expression and key protein content during the filling stage, which provided a guarantee for the improvement of photosynthesis. Compared with CTP, the activities of PPDK, PEPC, and Rubisco in maize leaves treated with NTP increased by 18.9%, 20.0%, and 30.6% on average, respectively, the gene expression of pepc, ppdk, and rub in maize leaves increased by 22.1%, 75.8%, and 70.6%, respectively, and the protein content of D1 and D2 in photosynthetic reaction center increased by 12.6% and 13.2%, respectively. Compared with CTP treatment, the activities of PPDK, PEPC and Rubisco in maize leaves under RTP increased by 15.6%, 16.4%, and 19.2%, respectively. The expression levels of pepc, ppdk, and rub genes in maize leaves increased by 13.6%, 53.9%, and 57.7%, respectively. The content of D1 protein in photosynthetic reaction center increased by 10.1%. In addition, the grain yield of NTP was 5.2%, 6.0%, and 5.3% higher than that under CTP in 2021, 2022, and 2023, respectively. The grain yield of RTP was only 5.2% higher than that under CTP in 2022. 【Conclusion】No-tillage with plastic re-mulching and using was an effective cultivation and management measure to maintain high photosynthetic performance, reduce plastic input, and increase maize yield in the northwest oasis irrigation areas.
【Objective】In the context of global climate change, frequent extreme rainfall has exacerbated farmland waterlogging, which severely restricts high and stable yields of maize. This study aimed to elucidate the regulatory mechanisms of calcium peroxide (CaO2) application on root morphology and yield formation in summer maize under waterlogged field conditions, for providing the theoretical support for stress-resistant and stable-yield cultivation of maize under waterlogging stress. 【Method】The experiment was conducted at the Huang-Huai-Hai Regional Maize Technology Innovation Center, Shandong Agricultural University during the 2023-2024 summer maize growing season. Using the maize variety Denghai 605 (DH605) and a randomized complete block design, treatments consisted of CaO2 application and a non-amended control (CK). At the V3 stage of summer maize, artificial waterlogging was simulated. The effects of CaO2 application were systematically investigated on: (1) soil oxygen concentration in the 0-40 cm profile; (2) maize root morphology parameters (total root length, total root surface area, total root volume, root dry weight); (3) leaf area index (LAI), SPAD value, photosynthetic parameters (net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr)) and aboveground dry matter accumulation; and (4) grain filling characteristics, yield formation. 【Result】Under waterlogging stress, two-year results indicate that CaO2 application significantly improved the soil oxygen environment. During a total of 10 measurements from the start of the treatment to 10 days after the end of the treatment, the average oxygen content in the 0-20 cm and 20-40 cm soil layers increased by 7.38% and 7.44%, respectively, compared with the control (CK), averaged over two years. Root morphology was markedly altered: at the flowering stage, total root length, total root surface area, total root volume, and root dry weight increased by 51.63%, 44.10%, 39.81% and 51.98% versus CK, respectively; canopy photosynthetic performance was significantly enhanced: maximum LAI and SPAD value at the flowering stage increased by 11.28% and 11.61%, respectively. At the flowering stage, the Pn, Gs, and Tr of the ear leaf increased by 23.84%, 30.63%, and 85.99%, respectively, while dry matter accumulation at maturity increased by 31.51%. Grain filling parameters improved: maximum grain filling rate, mean grain filling rate, grain weight at maximum filling rate, and grain weight at maturity increased by 7.29%, 7.29%, 5.81%, and 6.24%, respectively, compared with CK. CaO2 synergistically increased kernel number per ear and 1000-grain weight, with average two-year increases of 39.98% and 5.00%, respectively, ultimately increasing grain yield by 50.77% under CK. 【Conclusion】Calcium peroxide application mitigated waterlogging stress and enhanced grain yield in summer maize by optimizing soil oxygen environment, remodeling root morphology, improving canopy photosynthetic efficiency and increasing dry matter accumulation, thereby increasing the grain-filling rate. This measure significantly increased grain yield by simultaneously increasing kernel number per ear and 1000-grain weight. This study provided a novel agronomic approach for stabilizing and increasing maize yield under waterlogging stress at the seedling stage.
【Objective】Stay-green trait is an important agronomic characteristic closely related to high yield, good quality, and stress resistance of maize. This study explored the differences in nitrogen uptake and translocation of different stay-green maize hybrids, aiming to provide a theoretical basis for the physiological mechanism of high nitrogen efficiency in maize. 【Method】The tested materials were the stay-green hybrid Shandan 650 and the non-stay-green hybrid Zhengdan 958. In 2023, 6 N treatments were applied: N1 (0 kg·hm-2), N2 (60 kg·hm-2), N3 (120 kg·hm-2), N4 (180 kg·hm-2), N5 (240 kg·hm-2), and N6 (300 kg·hm-2). In 2024, a nitrogen×density interaction experiment was conducted with three N levels—low N (LN, 0 kg·hm-2), medium N (MN, 180 kg·hm-2), and high N (HN, 240 kg·hm-2)—and two planting densities—low density (LD, 60 000 plants·hm-2) and high density (HD, 75 000 plants·hm-2). After the silking stage of maize, indicators were determined for each treatment, such as SPAD value of ear leaves, total number of green leaves per plant, dry matter, and nitrogen accumulation in vegetative organs and grains. Meanwhile, nitrogen absorption and translocation rates as well as nitrogen use efficiency-related indicators were analyzed. 【Result】 Grain yield of both hybrids initially increased and then stabilized with rising N rates, with Shandan 650 consistently outperforming Zhengdan 958 across all N and density treatments. Post-silking, Shandan 650 exhibited faster chlorophyll degradation (SPAD decline: 65.1% vs. 49.9%) and greater green leaf loss than Zhengdan 958, particularly under low N. Shandan 650 demonstrated superior N remobilization efficiency, especially under low N and high density, with significantly higher N translocation from leaves to grains. Overall, Shandan 650 achieved significantly higher N remobilization efficiency, nitrogen use efficiency, nitrogen agronomic efficiency, and nitrogen harvest index than Zhengdan 958. Furthermore, under high-density planting conditions, reasonable nitrogen reduction further enhanced its nitrogen efficiency performance. 【Conclusion】 The functional stay-green maize variety Shandan 650 maintains consistent greenness and photosynthetic capacity until a certain period before physiological maturity, at which point a rapid decline occurs along with nitrogen remobilization. Its strong nitrogen translocation capacity in vegetative organs enhances nitrogen translocation rate and nitrogen use efficiency, and higher nitrogen efficiency could be achieved under reasonable nitrogen reduction and density increase.
【Objective】The objective of this study is to clarify the population dynamics and migration patterns of Harmonia axyridis under light traps in Luohe City, Henan Province, analyze their changing trends, and to provide data support for the effective protection and utilization of H. axyridis for biological control. 【Method】From 2015 to 2024, systematic monitoring of H. axyridis was conducted in Luohe City, Henan Province, using searchlight traps and ground light traps. From March 1 to November 30 each year, the number of H. axyridis under the two types of traps was sorted and counted daily. Based on the annual and monthly trapping amounts, as well as the first and last capture dates under the two traps, the patterns and trends of H. axyridis phototaxis were analyzed. The population dynamics of H. axyridis were examined based on the daily trapping percentage relative to the annual total and the distribution of peak occurrence days across different seasons. Additionally, the migration patterns of H. axyridis were analyzed using the optimized ratio of trapping amounts between searchlight traps and ground light traps. 【Result】Over the 10-year period, the searchlight traps accumulated a total of 19 771 H. axyridis individuals, while the ground light traps accumulated 11 061 individuals. The number of insects caught by the searchlight traps showed a significant decreasing trend, whereas the number caught by the ground light traps showed a significant increasing trend. The annual catches of the two types of traps exhibited a significant negative correlation (P<0.05). Except for the years 2021-2023, when the ground light traps captured more individuals than the searchlight traps, the searchlight traps captured more individuals in all other years. H. axyridis was detected over a longer period under the searchlight traps, with the first occurrence date approximately 20 days earlier and the last occurrence date about 19.5 days later compared to the ground light traps. There were exceptionally high peak capture days under the searchlight traps, while no such phenomenon was observed under the ground light traps. Under the searchlight traps, H. axyridis exhibited three peak periods: late May to mid-June, mid- to late July, and late September to mid-October, with the highest capture occurring from late May to mid-June. The peak capture days for the ground light traps were concentrated from early June to mid-August, with no distinct peak periods, though the highest capture occurred from late July to mid-August. The air-to-ground ratio indicated three migration peaks for H. axyridis: late May to early June, early to mid-July, and mid-September to late October, with the highest migration intensity observed in October. Over the past decade, the southward migration of H. axyridis has significantly decreased, and the annual migration days have shown a significant declining trend (P<0.01). 【Conclusion】There are notable differences in the annual capture numbers and population dynamics of H. axyridis between searchlight traps and ground light traps. The peak periods under searchlight traps are more distinct and exhibit sharper increases and decreases. The earlier first occurrence and later last occurrence dates under searchlight traps make them more advantageous for monitoring H. axyridis migration. Influenced by global warming, the occurrence of H. axyridis in Luohe is increasing, while its migration is decreasing. The combined use of searchlight traps and ground light traps allows for a more precise analysis of migration behavior and quantification of migration intensity.
