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10 November 2026, Volume 40 Issue 6 Previous Issue   
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Reviews and Special Topics

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Research Progress of the Functions of E3 Ubiquitin Ligases in Rice HAO Qixian, ZHOU Kunneng, YUN Peng, ZHANG Caijuan, XIA Jiafa, LI Zefu 2026, 40(6): 705-725.  DOI: 10.16819/j.1001-7216.2026.250616 Abstract ( )   HTML ( )   PDF (4797KB) ( )   E3 ubiquitin ligases determine substrate specificity and therefore play important roles in the ubiquitination process. Rice is one of the most important cereal crops, and recent studies have shown that E3 ubiquitin ligases are involved in regulating various biological processes in rice. This manuscript summarizes the reported E3 ubiquitin ligase genes in rice, elucidates the molecular mechanisms of E3 ubiquitin ligases in regulating rice growth, development, and stress response, and outlines further research prospects on E3 ubiquitin ligases, aiming to provide a theoretical basis and practical guidance for high-yield and stress-resistant breeding of rice.

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Genetic Basis and Breeding Applications of Grain Number per Panicle in Rice LI Hongzhou, CHEN Jiale, Muhammad ZUBAIR, ZHANG Jian, YANG Longwei, YING Jiezheng 2026, 40(6): 726-741.  DOI: 10.16819/j.1001-7216.2026.251208 Abstract ( )   HTML ( )   PDF (838KB) ( )   Rice grain number per panicle is a key component determining rice yield. Genetic studies and breeding practices have demonstrated that increasing grain number per panicle can effectively enhance grain yield per unit area. The formation of grain number per panicle involves complex physiological processes, including the differentiation and degeneration of the panicle meristem, source-sink allocation and assimilate balance, and the coordinated action of multiple phytohormone signaling pathways. Adequate assimilate supply, a well-developed vascular system, and suitable environmental conditions together constitute the physiological basis for grain number formation. To date, many genes controlling grain number per panicle have been cloned and characterized, which regulate grain number by influencing panicle architecture, meristem activity, branch differentiation, floral organ development, and hormone metabolism. More importantly, these genes form intricate regulatory networks, within which many genes exhibit pleiotropic effects on other agronomic traits, such as tiller number, grain shape, and heading date etc., resulting in trade-offs and synergistic effects. Based on the elucidation of the functional mechanisms and regulatory networks of these genes, breeders have applied grain number-related genes in rice genetic improvement through molecular design breeding, pyramiding of elite alleles, and genome editing approaches. This review systematically summarizes recent advances in the physiological and genetic bases of grain number per panicle formation in rice, outlines the application of grain number-controlling genes in rice variety improvement in China, and discusses future research directions and prospects for molecular breeding.

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Progress in Adaptive Mechanisms and Molecular Regulation of Submergence Tolerance in Rice HOU Yingxiang, FEI Sitian, CHEN Haibo, SUN Qing, WANG Weiping, ZHANG Chao 2026, 40(6): 742-755.  DOI: 10.16819/j.1001-7216.2026.250905 Abstract ( )   HTML ( )   PDF (856KB) ( )   Global climate change is intensifying, with frequent extreme rainfall events posing severe challenges to rice production. As a semi-aquatic crop, rice has evolved complex submergence tolerance mechanisms to cope with flood stress. This review summarizes the submergence adaptation mechanisms of rice from three aspects: morphological structure, hormone signaling, and metabolic regulation. Morphologically, rice optimizes oxygen acquisition and transport through internode elongation, adventitious root formation, and radial oxygen loss barriers; in hormone signaling, the "ethylene-gibberellin" positive feedback drives rapid internode elongation (escape strategy), while the submergence-tolerant gene Sub1A-1 inhibits this pathway to maintain growth quiescence (quiescence strategy), with abscisic acid, auxin, and other hormones involved in synergistic regulation; metabolically, during submergence, rice relies on the CBL-CIPK15-SnRK1A-MYBS1 pathway to activate starch degradation and promote anaerobic germination, and after de-submergence, Sub1A-1 regulates the restart of the TCA cycle and ROS scavenging to restore homeostasis. Finally, this review points out the deficiencies in current research and puts forward prospects for future studies, aiming to provide references for the improvement of rice submergence tolerance.

Research Papers

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Gene Cloning and Function Analysis of Small and Round Grain Mutant srg10 in Rice ZHAO Dongsheng, LI Yufan, ZHAO Beibei, ZHANG Tao, LI Qianfeng, LIU Qiaoquan 2026, 40(6): 756-766.  DOI: 10.16819/j.1001-7216.2026.250707 Abstract ( )   HTML ( )   PDF (3644KB) ( )   【Objective】Small and round grain mutants serve as ideal genetic materials for dissecting the regulation mechanism of rice grain size and can provide new breeding material for yield improvement.【Method】BSA-Seq was employed to delimit the causal locus in the small and round grain mutant srg10. Candidate gene was functionally verified by CRISPR/Cas9-mediated knockout. The phenotypic effects of srg10 on the main yield-related traits were identified, and the underlying mechanism modulating grain size was investigated.【Result】The srg10 mutation significantly reduced grain number per panicle and grain weight, resulting in a pronounced yield penalty. A single nucleotide substitution (SNP, G>A) within the Os10g0363700 gene was identified as the cause for the small and round grain phenotype. Comparative transcriptome profiling of young panicles from srg10 and wild-type plants revealed 292 differentially expressed genes (DEGs). GO enrichment analysis showed that these DEGs are predominantly associated with biological processes such as cell development, cell growth, and signal transduction. Expression profiling of known grain size genes further suggested that the srg10 mutation may involve multiple regulatory pathways such as cell cycle, transcriptional regulation, RNA splicing, and plant hormones, thereby modulating panicle development.【Conclusion】Mutation of Os10g0363700 produces pleiotropic, yield-adverse phenotypes characterized by small and round grains. RNA-Seq analysis showed that the mutant gene may be related to cell microfilament organization, and may also directly or indirectly regulate grain size via known grain size genes.

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Molecular Mechanism of OsPAL6-OsPetc Interaction in Rice Response to Rhizoctonia solani Infection WEI Songhong, WANG Yiming, LUO Hang, ZHANG Liangkun, WANG Mengyu, WANG Yan 2026, 40(6): 767-773.  DOI: 10.16819/j.1001-7216.2026.251203 Abstract ( )   HTML ( )   PDF (2809KB) ( )   【Objective】 Rice sheath blight, caused by Rhizoctonia solani, is one of the most devastating rice diseases worldwide, significantly impacting rice yield. Investigating the function of rice phenylalanine ammonia-lyase encoding gene OsPAL6 in the rice-Rhizoctonia solani interaction and exploring the disease resistance pathways potentially involving OsPAL6 and OsPetc is of great importance. 【Method】 OsPAL6 was initially identified based on previous transcriptome data of resistant and susceptible rice varieties inoculated with Rhizoctonia solani. Subsequently, RT-qPCR was performed to verify whether OsPAL6 responds to sheath blight pathogen infection and to determine its relative expression levels in different tissues. A subcellular localization vector for OsPAL6 was constructed to determine its localization in tobacco cells. OsPAL6-overexpressing transgenic rice lines were generated, and detached leaves from different lines were inoculated with Rhizoctonia solani to measure the relative lesion area. Furthermore, a yeast two-hybrid library screen was performed to identify potential interacting proteins of OsPAL6. The interaction between OsPAL6 and OsPetc was confirmed using yeast two-hybrid(Y2H) and bimolecular fluorescence complementation (BiFC) assays. 【Result】 OsPAL6 responded to Rhizoctonia solani infection at all tested time points, with the highest relative expression level observed in leaves. Subcellular localization analysis revealed that OsPAL6 was localized in both the nucleus and the cytoplasmic membrane. Overexpression lines exhibited a significantly smaller relative lesion area compared to wild-type plants, whereas mutant plants showed a significantly larger relative lesion area. Furthermore, an interaction between OsPAL6 and OsPetc was demonstrated. 【Conclusion】 OsPAL6 positively regulates rice resistance to sheath blight. This function is likely mediated through its interaction with OsPetc. In summary, this study reveals the regulatory network involving the phenylalanine metabolic pathway in the defense against sheath blight and provides new insights into the interaction mechanism between rice and Rhizoctonia solani.

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Genotyping and Breeding Utilization of Parental Lines of japonica Hybrid Rice in Shanghai Based on High-Density SNP Chips NIU Fuan, CHU Huangwei, ZHANG Anpeng, ZHOU Jihua, SUN Bin, DAI Yuting, XIE Kaizhen, SHI Fengzhen, YIN Zihui, HOU Cong, WANG Yi, LI Jing, CHENG Can, CAO Liming 2026, 40(6): 774-785.  DOI: 10.16819/j.1001-7216.2026.260412 Abstract ( )   HTML ( )   PDF (1120KB) ( )   【Objective】To elucidate the genetic characteristics of major parental lines of japonica hybrid rice in Shanghai at the genomic level, thereby providing a theoretical basis and germplasm resources for the molecular improvement of these parental lines and evaluation of new hybrid combinations.【Method】High-density rice whole-genome SNP chips were employed to analyze the genetic background, identify functional genes, and assess the breeding value of 20 major parental lines of japonica hybrid rice in Shanghai.【Result】The sterile lines of japonica hybrid rice generally exhibited a higher proportion of japonica components than the restorer lines. Among them, Shen 68A, Shen 01A, Shen 9A, Shen 10A, Shen 21A, Shen 46A, Shenwu 1A, Shenchang A, and Zixiang A showed a particularly high ratio of japonica genome segments and were classified as typical japonica types. A total of 19 and 35 functional genes controlling key traits such as yield, quality, and resistance to biotic and abiotic stresses were detected in the 11 sterile lines and 9 restorer lines, respectively. The major sterile lines of japonica hybrid rice in Shanghai exhibited favorable disease resistance. Several lines, including Shen 68A, Shen 9A, Shen 10A, Shen 21A, Shen 130A, and Shen 24A, carried the broad-spectrum blast resistance gene combination Pi2+Pita. The restorer lines featured large panicles and high spikelet numbers, harboring multiple yield-related genes (OsSPL16, Gn1a, CYP704A3, etc.). However, few restorer lines aggregated multiple major broad-spectrum blast resistance genes, indicating a need to strengthen molecular improvement for blast resistance in restorer lines.【Conclusion】This study clarifies the genetic backgrounds and functional gene profiles of major parental lines of japonica hybrid rice in Shanghai, laying a solid foundation for improving breeding efficiency and addressing genetic homogeneity in hybrid rice breeding.

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Effects of Alternate Wetting and Drying Irrigation on Grain Yield and Quality of Rice in Heilongjiang Province GAO Lingxiao, YE Fan, LI Shuai, CHEN Yun, LIU Lijun 2026, 40(6): 786-795.  DOI: 10.16819/j.1001-7216.2026.260106 Abstract ( )   HTML ( )   PDF (532KB) ( )   【Objective】To address the ambiguity regarding optimal water control thresholds for alternate wetting and drying (AWD) irrigation in the rice-growing regions of Heilongjiang Province, this study aimed to identify an irrigation regime that synergizes high grain yield with superior quality, thereby providing a theoretical framework for sustainable rice production in the region.【Method】Utilizing the conventional japonica rice cultivar ‘Longjing 31’ as experimental material, field trials were conducted at Qixing Farm, Jiansanjiang Branch of Beidahuang Group, Jiamusi City, Heilongjiang Province. The effects of mild (MID), moderate (MOD), and severe (SED) AWD irrigation on rice yield and grain quality were systematically evaluated.【Results】1) Regarding yield and irrigation efficiency, the MID treatment significantly enhanced grain yield by 6.90%-11.89% compared to the local conventional flooding (CF) practice. The MOD treatment exhibited no significant impact on yield, whereas the SED treatment resulted in a significant yield reduction of 6.30%-6.70%. Over the two-year period, the MID treatment significantly improved irrigation water use efficiency by 22.42%-35.46% and reduced irrigation water consumption by 12.21%-16.23%, demonstrating substantial water-saving and efficiency-enhancing effects. 2) In terms of grain quality, the MID treatment reduced the chalky grain rate and markedly improved the appearance quality of rice, while maintaining milling and cooking/eating qualities comparable to those of the CF treatment. The MOD treatment exhibited a tendency toward quality deterioration. Conversely, the SED treatment significantly reduced the milled rice rate, head rice rate, and amylose content, leading to deterioration in milling quality and eating quality.【Conclusion】The MID treatment facilitates the synergy between high yield and superior quality, representing an optimal high-yielding, high-efficiency, and water-saving irrigation method for the rice-growing regions of Heilongjiang Province.

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Effects of Nitrogen Fertilizer Combined with Organic Fertilizer Application on the Yield and Grain Quality of Perennial Rice 26 GUO Jintao, KONG Yanhong, LI Lianxiang, ZHOU Yan, YU Xuefei, HUANG Guangfu, ZHANG Shilai, ZHANG Jing, HU Fengyi, ZHANG Yujiao 2026, 40(6): 796-807.  DOI: 10.16819/j.1001-7216.2026.251001 Abstract ( )   HTML ( )   PDF (885KB) ( )   【Objective】Perennial rice represents a novel rice cropping system characterized by continuous harvests following a single sowing event. From the second growing season onward, it eliminates conventional agronomic practices such as sowing, seedling nursing, tillage, and transplanting, thereby enabling significant cultivation simplification. Nitrogen is a critical nutrient that governs both grain yield and rice quality. The integrated application of nitrogen fertilizer and organic fertilizer has been demonstrated to synergistically enhance both productivity and grain quality in rice cropping systems. However, systematic investigations on the combined effects of nitrogen and organic fertilizers on the coordinated improvement of yield and quality in perennial rice remain limited. To address this knowledge gap, a field experiment was conducted from January 2023 to December 2024 in Menghai County, Yunnan Province, using the perennial rice variety “PR26” as the experimental material. The study aimed to evaluate the impacts of different nitrogen and organic fertilizer application strategies on grain yield and quality of perennial rice, with the goal of providing theoretical guidance for high-quality and sustainable perennial rice production.【Method】The experiment was conducted using a two-factor randomized complete block design. Three nitrogen fertilizer levels were applied: 0 (N0), 120 (N1), and 180 kg/hm2 (N2); and three organic fertilizer treatments were implemented: no organic fertilizer (F0), Heliwang organic fertilizer (F1), and Yuanjiang Nongzhuang organic fertilizer (F2). This resulted in a total of nine treatment combinations. 【Result】1) The combined application of nitrogen fertilizer and organic fertilizer significantly enhanced the effective panicle number, grains per panicle, and seed setting rate of PR26, with the N2F1 treatment achieving the highest values—304.94 panicles per m2, 116.06 grains per panicle, and 83.21%, respectively. Compared to the N0F0 control, effective panicle number and grains per panicle increased by 17.04% and 21.05%, respectively, while seed setting rate increased by 18.28 percentage points. 2) Grain yield of PR26 maximized under the N2F1 treatment, averaging 6.93 t/hm2 across four growing seasons. Nitrogen application rate was the primary factor influencing yield, with the average yield under N2 being 66.26% higher than N0 and 19.26% greater than N1. The yield-enhancing effect of organic fertilizer followed the order F1 > F2 > F0, where F1 increased yield by 7.77% and 3.64% relative to F0 and F2, respectively. 3) Photosynthetic performance and perenniality traits of PR26 differed significantly across fertilization treatments. During maturity, the N2F1 treatment exhibited markedly higher net photosynthetic rate, dry matter accumulation, and root bleeding sap flow, with mean values of 19.76 μmol/(m2·s), 24.42 t/hm2, and 0.54 g/h, respectively. 4) Increasing nitrogen supply significantly increased plant nitrogen concentration and nitrogen harvest index (NHI). The N2F1 treatment achieved the highest nitrogen use efficiency, with a plant nitrogen concentration of 3.07% and an NHI of 52.80%. 5) Co-application of nitrogen and organic fertilizers synergistically improved the processing, nutritional, and cooking quality of perennial rice PR26. Among the treatments, N2F2 performed best in brown rice rate, milled rice rate and amino acid content, with a brown rice rate of 87.96%, a milled rice rate of 77.35%, a head milled rice rate of 53.73%, a glutelin content of 5.21% and an amino acid content of 353.33 μmol/g.【Conclusion】The combined application of nitrogen and organic fertilizers synergistically enhances photosynthetic performance, promotes dry matter accumulation and nitrogen uptake, and optimizes yield components, thereby significantly increasing grain yield in perennial rice. This integrated fertilization strategy also improves ratoon survival rate and root system vitality, helping to sustain the crop's perennial characteristics, while concurrently improving rice quality in terms of milling, nutritional value, and cooking and eating quality.

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Effects of Microbial Inoculants on Cadmium Uptake, Accumulation, and Root Microbial Community in Rice TANG Hongwei, WU Yue, ZHU Xinxia, LIU Xuemei, YANG Qing, WANG Danying, LIU Yuanhui 2026, 40(6): 808-820.  DOI: 10.16819/j.1001-7216.2026.250615 Abstract ( )   HTML ( )   PDF (3821KB) ( )   【Objective】This study aims to investigate the effect of microbial inoculants on cadmium (Cd) uptake, accumulation, and the root microbial community in rice, providing a theoretical basis for applying green and efficient microbial agents to reduce Cd accumulation in rice grains.【Methods】A field experiment was conducted in Cd-contaminated paddy soil. Microbial inoculant treatments included: 1) seed coating for direct-seeded rice, and 2) foliar spray before transplanting, 3) seed coating + foliar spray 15 days after transplanting for transplanted rice. A control group received no inoculant. At maturity, Cd concentrations in soil, rice roots, stems/leaves, and grains were analyzed. High-throughput 16S rRNA amplicon sequencing was used to characterize microbial community structures in bulk soil, rhizosphere soil, and root endosphere under different treatments.【Results】Microbial inoculants significantly reduced Cd uptake and accumulation in rice. For transplanted rice (seed coating + foliar spray post-transplanting), the Cd uptake factor (UF) and bioaccumulation factor (BF) decreased by 41% and 69%, respectively, compared to the control. The BF in direct-seeded rice with seed coating decreased by 80%. However, no significant effect was observed on the translocation factor (TF). Microbiome analysis revealed that inoculants significantly increased the diversity of root endophytic microbial communities, particularly in transplanted rice. Taxa significantly enriched in the root endosphere under inoculant treatments showed increased relative abundance.【Conclusion】Microbial inoculants reduce Cd uptake by enhancing root endophytic microbial diversity and promoting competition for root binding sites. Furthermore, enriched root endophytic taxa may inhibit Cd absorption via redox reactions, adsorption, or bioaccumulation mechanisms.

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Development and Evaluation of Mechanized Cultivation Techniques for Film-mulched Dry Farming of Upland Rice LIU Haodong, DING Qishuo, CHEN Shaohua, LI Yinian, YAN Xiaoyuan, XU Gaoming, HE Ruiyin 2026, 40(6): 821-837.  DOI: 10.16819/j.1001-7216.2026.260114 Abstract ( )   HTML ( )   PDF (5053KB) ( )   【Objective】This study developed supporting machines for film-mulched dry farming of upland rice, and explored the effects of different mechanized cultivation techniques on machinery operation quality and agronomic effects including seedling emergence and yield, so as to provide a theoretical basis for machinery optimization and high-quality mechanical direct seeding.【Method】Two tested machines were developed for two operation modes, namely film-mulched dry direct seeding (MS) and dry direct seeding with film mulching (SM). Combined with three soil covering methods: full-film soil covering (1), strip soil covering (2), and no soil covering (3), six mechanized cultivation techniques were established [MS1, MS2, MS3, SM1, SM2, and non-mulched control (CK)]. Evaluation index systems for machinery operation quality and agronomic effects were constructed and used to investigate the impacts of different soil covering methods on machinery operation quality and of different mechanized cultivation techniques on agronomic effects. Statistical methods were used to explore the internal relationships among the indices.【Result】Different soil covering methods significantly affected machinery operation quality. Compared with MS3, MS1 and MS2 reduced the hole dislocation rate by 60.74%-71.45% and increased the seed covering thickness by 21.99%-31.59%. Their seeding operation quality was significantly better than that of MS3, and the seedling emergence rate was improved by 27.16%-32.23%. The film-soil contact degree of SM1 was 17.72% higher than that of SM2, and increased the seedling emergence rate by 6.81%. Significant differences in agronomic effects were found between the two operation modes: compared with MS, SM increased soil moisture content by 9.30%-22.00% and reduced weed density by 75.12%-79.24%, but decreased seedling emergence rate by 16.15%-18.37% and reduced grain yield by 4.31%-5.50%. Regarding the relationship between operation quality and agronomic effects, the correlation coefficients of hole dislocation rate and film-soil contact degree with seedling emergence rate were -0.949 and 0.818, respectively. Furthermore, seedling emergence rate was significantly positively correlated with effective panicle number and grain yield. The correlation patterns among indices varied with operation modes: seedling emergence and grain yield indices of MS were significantly correlated with multiple indices including operation quality and environmental factors, while those of SM were only significantly correlated with operation quality indices such as film-soil contact degree.【Conclusion】Dry direct seeding with film mulching and film-mulched dry direct seeding each have distinct technological advantages. Techniques should be selected and supporting machines optimized based on regional production conditions to maximize the agronomic benefits of mechanized cultivation. Meanwhile, the soil covering thickness on the film should be stably controlled at 15-20 mm to ensure the machinery operation quality and field seedling emergence.

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Development and Experiment of a Post-pollination Male Parent Harvester for Hybrid Rice Seed Production ZENG Zhijun, CHEN Xiongfei, LIN Jinlong, CAI Jinping, XIAO Liping, LI Yonghui, LIN Yihang, MIAO Kehao 2026, 40(6): 838-848.  DOI: 10.16819/j.1001-7216.2026.250705 Abstract ( )   HTML ( )   PDF (3048KB) ( )   【Objective】To realize the mechanized harvesting of male parents after pollination in hybrid rice seed production under a small row ratio planting mode,【Method】a male parent harvesting device for hybrid rice seed production was designed, which was composed of a double cutterhead cutting mechanism, a synchronous belt clamping and feeding mechanism, a double-roller spiral clamping and pulling mechanism and a spiral hob chopping mechanism, and the working performance test and field test of each mechanism were carried out.【Result】When the forward speed is 0.2 m/s, the overlap rate of double cutting blades is 4.14%, and the cutter speed is not less than 650 r/min, the cutting success rate of the double cutterhead can reach 100%. When the clamping thickness of the synchronous belt clamping feeding mechanism is 10 mm, the feeding success rate is up to 87.5%. When the length of the double drum clamping and pulling mechanism is 200 mm, the angle of the spiral guide bar is 30°, and the drum speed is 300 r/min, the stem pull-down success rate is 97.5%, and the working performance is the best. When the length of the spiral hob chopping mechanism is 200 mm and the speed is 200-300 r/min, the success rate of chopping can reach 96.5%, and the scattering distance meets the agronomic requirements.【Conclusion】The results of field experiment showed that the average chopping success rate of male parent straw was 99.52%, the average cutting success rate was 90.59%, and the harvesting effect was good.