Rice is one of the most important food crops globally, and its growth requires more water than many other crops. With global warming, drought has emerged as the main factor limiting crop yields. Therefore, based on recent research achievements, this paper summarizes the self-protection mechanisms of rice under drought stress. This includes aspects such as morphology (plant height, roots, leaves, number of tillers, and plant biomass), physiology (stomata, transpiration, photosynthesis, and water use efficiency), biochemistry (plant hormones, proline, other osmotic regulators, and antioxidants), and molecular biology (expression levels of drought resistance genes). The aim is to comprehensively understand rice's drought resistance mechanisms and provide a reference for breeding drought-resistant varieties

The production of rice in coastal saline-alkali lands is constrained by limited freshwater resources and water infrastructure. The presence of salinity damage and drought, often occurring together, renders rice production in these areas highly susceptible to combined salinity-drought stress, significantly impeding the attainment of high yield and quality in rice in coastal saline-alkali lands. A comprehensive analysis of the impacts of salinity damage, drought, and their combined stresses on rice yield and quality formation, along with their physiological mechanisms, can offer scientific backing for optimizing high-yield and quality rice cultivation in coastal saline-alkali lands. This article presents an overview of the effects of salinity damage, drought, and their combined stresses on the growth, development, yield formation, and grain quality of rice. The mechanisms underlying their influence on rice yield and quality formation are elucidated, focusing on osmotic regulation, ion balance, photosynthetic functions, antioxidant enzyme systems, endogenous hormones, key enzyme activities related to sucrose-starch metabolism, and molecular mechanisms. Recommendations are provided for the selection of salinity- and drought-tolerant varieties, as well as cultivation practices to mitigate salinity and drought stress in rice. Lastly, suggestions are proposed for further research on salinity and drought stress in rice.

【Objective】 Jasmonic acid (JA) plays crucial roles in plant growth and development, and responses to both biotic and abiotic stresses. OPR (12-oxo-phytodienoic acid reductase) serves as a pivotal enzyme in the JA biosynthetic pathway. In this study, transgenic rice plants overexpressing OsOPR10 were generated to assess their resistance to rice blast and bacterial blight. The research delved into the molecular mechanisms through which OsOPR10 regulates the defense response to these diseases.【Method】 Methodologically, the study involved the construction of OsOPR10 CRISPR/Cas9 knockout and overexpression vectors. These vectors were then utilized for Agrobacterium-mediated genetic transformation to obtain OsOPR10 knockout (OsOPR10-KO) and overexpressed (OsOPR10-OE) transgenic rice plants, using Nipponbare (NPB) as the wild-type parent. The transgenic plants underwent various assays to evaluate disease resistance, reactive oxygen species (ROS) burst, and the expression of genes related to the salicylic acid (SA) and jasmonic acid (JA) pathways. Additionally, the subcellular localization of OsOPR10 was examined using a laser confocal microscopy, and the interacting protein of OsOPR10 was identified through yeast two-hybrid screening and luciferase complementation experiments.【Result】 The results of the study indicated the successful generation of homozygous plants with OsOPR10 knockout and overexpression. Plants overexpressing OsOPR10 exhibited enhanced resistance to rice blast and bacterial blight. Upon induction with chitin and bacterial flagellin (flg22), ROS accumulation in OsOPR10-OE plants was notably higher than that in the wild type. Furthermore, qRT-PCR analysis revealed up-regulation of JA pathway genes (OsAOS2, OsAOC) and SA pathway genes (OsPR1a, OsPAL1) in OsOPR10-OE plants compared to NPB at 12 hours post-inoculation with Magnaporthe oryzae. Subcellular localization studies demonstrated that the OsOPR10 protein was localized in chloroplasts. The interaction protein OsCYP28 of OsOPR10 was identified through yeast two-hybrid assays and luciferase complementation experiments 【Conclusion】 In conclusion, OsOPR10 plays a significant role in responding to infections by Magnaporthe oryzae and Xanthomonas oryzae pv. oryzea, as well as to the application of exogenous methyl jasmonate (MeJA) and SA. OsOPR10 is involved in the pathogen molecular pattern-triggered immune pathway and positively regulates rice resistance to rice blast and bacterial blight through the JA and SA pathways. Additionally, OsOPR10 protein localizes in chloroplasts and interacts with the OsCYP28 protein.

【Objective】 Rice false smut, caused by Ustilaginoidea virens, is a global fungal disease that severely impacts rice yield and quality. Understanding the molecular mechanisms behind U. virens pathogenicity could inspire novel control strategies and molecular breeding for disease resistance. 【Method】 Transcriptome and metabolome analyses were conducted on the initial symptomatic panicle nine days after inoculation (S) and uninoculated PXD25 mycelium (CK). The genome of strain UV-8b served as the reference for sequence alignment. Gene expression levels were quantified using fragments per kilobase per million fragments (FPKM), and differentially expressed genes (DEGs) were identified using |LOG₂ fold change|≥1 and q-value≤0.05 criteria. Differentially accumulated metabolites (DAM) were identified with P≤0.05 and VIP≥1 thresholds. 【Result】 In the S vs. CK comparison, 6078 DEGs were identified. GO enrichment analyses revealed 3708 terms, and KEGG pathway analysis identified 110 metabolic pathways. Ninety-one transcription factors (TFs) belonging to 23 TF families, such as bZIP and C2H2, were among the DEGs. Significant enrichment of mitophagy, secondary metabolism, and amino acid metabolism pathways was observed, with upregulation of DEGs in secondary metabolic pathways suggesting their crucial role in U. virens pathogenesis. Additionally, 392 DAMs were identified, including alanine, tyrosine, histidine, methionine, cysteine, and fatty acids (linoleic acid, palmitic acid, lauric acid, myristic acid), indicating their association with U. virens pathogenicity. Combined transcriptome and metabolome analysis highlighted enrichment in amino acid metabolic pathways (e.g., phenylalanine, tyrosine, cysteine, and methionine) and carbohydrate-related pathways (e.g., starch and sucrose). 【Conclusion】 DEGs involved in mitophagy, secondary metabolism, and amino acid metabolism, along with DAMs like alanine, tyrosine, histidine, methionine, cysteine, and fatty acids, are closely linked to U. virens pathogenicity.

【Objective】 The objective of this study is to investigate the distribution of inter-subspecific fertility loci in indica rice, japonica rice, and indica-japonica hybrid rice in China. This involves establishing a pattern of fertility loci to achieve compatibility between different subspecies, exploring new indica-japonica hybrid rice patterns, and laying a molecular basis for improving materials and breeding designs for inter-subspecific compatibility.【Method】 Specific markers for indica and japonica rice were used to screen for inter-subspecific fertility loci in rice materials from China. Several indica and japonica rice varieties were crossed with each other, and the pollen fertility and seed setting rate of the resulting hybrids were statistically analyzed.【Results】 There was limited genetic exchange between indica and japonica rice at the fertility loci. Due to introgression of fertility loci from indica rice, japonica rice could be classified into type I (pure japonica) and type II (with introgressed indica loci such as Scⁱ, Sdⁱ, and Seⁱ). When S5 was incompatible, the seed setting rate of inter-subspecific hybrid rice was approximately 50%, while it increased to about 80% when compatible. Heterozygosity at Sa, Sb, Sc, or Sd loci had minimal impact on pollen fertility, but heterozygosity of Se/pf12/RHS12 significantly reduced it. The detection results of inter-subspecific hybrid rice materials indicated that the basic fertility loci pattern was homozygous or compatible S5 along with several other fertility loci for pollen fertility. The pollen fertility and seed setting rate of F₁ hybrids from the indica two-line male sterile line Shen 08S with S5ⁿ and japonica type II rice were normal.【Conclusion】 SS5 is the core locus controlling female gamete fertility, while loci affecting male gamete fertility have an additive effect. Se may be an indispensable locus among them. The possible basic genetic locus patterns for achieving fertility compatibility between indica and japonica subspecies include S5+Se+two other loci among Sa, Sb, Sc, and Sd. The ‘maternal indica paternal japonica’ model, utilizing two-line indica rice male sterile lines with wide compatibility as female parents and japonica rice as male parents, presents another feasible inter-subspecific hybrid rice model.

【Objective】 The Jiahe series long-grain japonica rice is renowned for its slender grain shape, exceptional appearance quality, superior eating quality, high yield, and high disease resistance. This study aimed to elucidate the distinctive characteristics and challenges of these rice varieties, analyze the genetic foundation for the development of high-quality traits in these varieties, and lay a foundation for the innovation and utilization of long-grain japonica rice varieties. 【Method】 We utilized the GSR40K high-density rice chip to ascertain the indica-japonica identity and variety similarity of five long-grain japonica rice varieties (lines) of Jiahe series, and identified breeding-related functional genes. Furthermore, the genetic basis of the Jiahe series long-grain japonica rice was compared with that of the long-grain japonica rice Daohuaxiang 2 from Northeast China. 【Result】 The japonica segments in the genome of the Jiahe series long-grain japonica rice accounted for 84.20% to 88.38%, indicating the classification of these varieties into typical japonica rice types. The genetic similarity of Jiahe series japonica rice varieties (lines) exceeded 92%, with genomic identity ranging from 77.59% to 91.73%, while the similarity with Daohuaxiang 2 was lower, averaging 84.55% genetic similarity and 49.52% to 53.68% genome identity. Jiahe series japonica rice contains functional alleles for long grain genes gs3 and GW7, as well as the large grain type gene qSW5/GW5 and the multi-spikelet number gene LAX1 in Jiahexiang 1. The development of fine quality traits is mainly attributed to the combination of ALK^c/Wx^b/OsAAP6 and other major functional alleles. The fragrance in Jiahexiang 1 resulted from the exon 2 mutation type of the Badh2 gene. Jiahe series long-grain japonica rice varieties (lines) harbor numerous blast resistance genes, such as the combinations Pizt+Pii/HIT7/pi5-1, Pizt+Pii/HIT7/pi5-1, Pizt+Pi-ta, and Pizt+Pii/HIT7/pi5-1+Pi-d2/Pid2+Pid3+Pi-ta. In contrast, Jiahe series japonica rice only possesses Xa26/Xa3 genes for white leaf blight resistance. 【Conclusion】 The exceptional advantages of Jiahe series long-grain japonica rice stem from the comprehensive impact of multiple favorable allelic gene variations on yield, quality, resistance, and agronomic traits. Nonetheless, there are drawbacks of high variety similarity and a solitary gene for white leaf blight resistance. The findings of this study also furnish a scientific basis for the genetic enhancement of Jiahe series long-grain japonica rice varieties.

【Objective】 Salt stress is one of the important environmental factors limiting the yield and quality of crops, including rice. Developing risk cultivation techniques that enhance salt tolerance in rice is essential for ensuring food security in China. 【Methods】 In this study, Nipponbare was selected and subjected to salt stress at the seedling stage. Potassium fulvic acid (PFA) was exogenously sprayed onto rice seedling plants, with distilled water used as a control. The first fully expanded leaves were sampled to determine physiological parameters, including dry biomass, photosynthesis, carbohydrates contents, energy metabolism, Na⁺/K⁺ ratio, and antioxidant enzyme activities during salt stress.【Results】 Under salt stress, the dry biomass and plant height of rice seedlings treated with PFA were significantly higher than those treated with distilled water. Compared to the control, the relative electrolyte leakage, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) contents in the PFA-treated group were significantly lower than those in the water-treated group, indicating a stronger antioxidant capacity in the former. After salt stress treatment, the decrease in leaf chlorophyll content, actual photochemical quantum efficiency, relative electron transport rate, and net photosynthetic rate were lower in the PFA-treated group than in the water-treated group. There was no obvious difference in the contents of carbohydrates in leaves between these two treatments; PFA effectively reduced the inhibition of energy metabolism by salt stress. It was found that the PFA-treated seedling plants exhibited significantly lower decreases in leaf ATP content, energy charge, and ATPase activity compared to the water-treated group under salt stress. Correspondingly, the increment in potassium ion concentration and decrement in sodium ion concentration in the PFA-treated group were higher than those in the water-treated group. 【Conclusion】 Potassium fulvic acid can improve leaf photosynthesis, promote ATP production and utilization, enhance antioxidant capacity, maintain a higher potassium ion concentration, and lower reactive oxygen species and sodium ion concentrations under salt stress. This, in turn, mitigates damage to rice seedling plants caused by salt stress, providing technical and theoretical support for the development of salt tolerance cultivation techniques and chemical regulators for rice seedlings.

【Objective】 To elucidate the yield formation characteristics of small-seed hybrid rice.【Method】 Zhuoliangyou 0985 (small-seed hybrid rice variety) and Fengliangyou 4 (control variety) were utilized as materials for a field experiment at varying nitrogen application rates (0, N0; 180 kg/hm², N1; 210 kg/hm², N2) and densities (26.7 cm×20.0 cm, D1; 20.0 cm×20.0 cm, D2; 20.0 cm×16.7 cm, D3)【Result】 The leaf area index (LAI) and leaf SPAD values of the two varieties increased with nitrogen application rate, with no significant difference between N1 and N2, but significantly higher than N0 treatment. The dry matter output rate of stems and sheaths decreased with rising nitrogen application, while leaf matter output rate followed the opposite trend. Grain yield of both varieties increased with increasing nitrogen application, with no significant difference between N1 and N2. Among different density treatments, D2 generally yielded higher results. Under N0 treatment, Zhuoliangyou 0985 had significantly higher yield than the control variety, while under nitrogen application conditions, both varieties had equivalent yields. 【Conclusion】 The yield formation characteristics of Zhuoliangyou 0985 include smaller leaf area, more grains per panicle, larger sink-source ratio, noticeable photosynthetic advantages during mid to late grain filling stages, higher post-flowering substance accumulation and transport rate of stem and leaf substances, higher harvest index, and increased yield under nitrogen-deficient conditions. In the context of this experiment, N1D2 (180 kg/hm², 20cm×20cm) emerged as the optimal treatment for Zhuoliangyou 0985.

【Objective】 Studying the regulatory effects of rhizosphere saturated dissolved oxygen (RSDO) during the tillering stage on rice photosynthesis and chlorophyll fluorescence parameters is of great significance for improving rice light energy utilization efficiency and optimizing rice oxygen nutrition cultivation theory.【Method】 This study conducted a hydroponic experiment using three ecological types of rice varieties, namely lowland rice, deep-water rice, and upland rice, as experimental materials. Two treatments, rhizosphere saturated dissolved oxygen (RSDO) and natural growth (CK), were set up to measure chlorophyll fluorescence parameters, photosynthetic characteristics, and dry matter accumulation during the rice tillering stage.【Result】 Under the conditions of rhizosphere saturated dissolved oxygen, the leaf light response curves of lowland rice and deep-water rice decreased. When the light intensity exceeded 500 μmol/(m²·s), the difference in curves with the control group increased. The fitting of the light response curve indicates that rhizosphere saturated dissolved oxygen reduces the maximum net photosynthetic rate (P_nmax), apparent quantum efficiency (Q), dark respiration rate (R_d), and light compensation point (LCP) of rice leaves. The maximal photochemical efficiency (F_v＇/F_m＇), the actual photochemical efficiency (Φ_PSⅡ), electron transfer rate (ETR), and photochemical quenching coefficient (q_P) of the three rice varieties under RSDO were lower than those of CK, while the non-photochemical quenching (NPQ) and 1－q_P were increased. Rhizosphere saturated dissolved oxygen can increase the nighttime respiration rate (R_n) and intercellular CO₂ concentration (C_i) of rice. The leaf chlorophyll a, chlorophyll b, and total chlorophyll contents of three rice varieties all showed RSDO < CK, while carotenoid content and relative conductivity showed RSDO > CK. The saturated dissolved oxygen in the rhizosphere significantly reduced the aboveground dry matter mass and leaf area index of lowland rice and deep rice, with a decrease of 12.6%, 9.4%, and 9.2%, 6.6%, respectively, compared to the control. There was no significant difference between the treatments of upland rice varieties.【Conclusion】 RSDO inhibits the synthesis of photosynthetic pigments in rice leaves, reduces leaf PSⅡ performance and light energy utilization efficiency, which is not conducive to early rice growth. Compared to lowland rice and deep-water rice, upland rice has better adaptability to RSDO.

【Objective】 Weedy rice poses a significant threat to rice production in direct-seeded rice fields, resulting in substantial yield losses. Analyzing the occurrence patterns, diversity changes, and genetic evolution of weedy rice populations in these fields is crucial for managing agricultural ecosystems effectively and preventing weedy rice disasters.【Methods】 This study conducted a continuous three-year fixed-site survey of weedy rice populations in new direct-seeded rice field ecosystems. Through targeted sampling, phenotypic characterization, and population genetic structure analysis using liquid chip technology, we examined the scale of damage, ecological types, and genetic diversity evolution of weedy rice populations. 【Results】 In direct-seeded rice fields, the weedy rice population increased annually, with densities of 345.6 plants/m², 512.4 plants/m², and 600.1 plants/m², respectively. Phenotypic diversity showed a consistent upward trend, with Shannon-Wiener (H') indices of 0.530, 0.762, and 0.852, and Simpson (D) indices of 0.340, 0.227, and 0.164. Genetic diversity (Pi) initially increased and then declined over the three years, with values of 0.2097, 0.2530, and 0.1493, respectively. At the population genetic structure level, both principal component analysis (PCA) and phylogenetic tree analysis consistently indicated that weedy rice was not directly related to locally cultivated rice. Weedy rice samples from different years were distributed across major clustering branches. Various types of weedy rice underwent natural selection due to the cold environment and competition with direct-seeded rice, leading to a survival-of-the-fittest scenario. This process results in rapid convergence, increased genetic diversity, alterations in population genetic structure, and the emergence of adaptive types.【Conclusion】 Weedy rice invasion in direct-seeded rice fields leads to rapid population expansion and diversity increase, escalating the disaster index swiftly. Genetic diversity and population genetic structure are highly sensitive to selection pressure, suggesting that harmful adapted weedy rice types are established early in their invasion into direct-seeded rice field ecosystems.

【Objective】 To investigate the species, distribution, and occurrence of cyst nematode disease on rice in Guangdong Province. 【Methods】 A total of 231 rice roots and rhizosphere soil samples from 14 cities in Guangdong Province were collected and analyzed. The cyst nematode species in these samples were identified through morphological and molecular identification. 【Results】 Cyst nematodes were found on rice in Qingyuan, Zhaoqing, and Jiangmen in Guangdong Province, with detection rates of 40%, 23.7%, and 10%, respectively. Morphological identification revealed that the cysts were lemon to spherical-shaped, predominantly lemon-shaped, with an ambifenestrate vulval cone, a nearly round fenestral, a narrow vulval bridge, and a medium-sized underbridge. The second-stage juvenile (J2) had a hemispherical and offset labial region, a conical tail with a pointed tip, and a hyaline region occupying 53% to 66% of the tail length. Molecular identification indicated that the 28S rDNA D2-D3 region of the cyst nematode was 99.73%－100% similar to Heterodera elachista in the NCBI database, and the rDNA-ITS region was 96.72%－99.91% similar to Heterodera elachista in the NCBI database. Phylogenetic analysis placed the nematode in the same branch as H. elachista with a confidence level of 100%. Using specific primers He-F/He-R of H. elachista, a 281 bp single band was amplified from the rDNA-ITS region of the cyst nematodes, consistent with previous reports. 【Conclusion】 The cyst nematodes collected in Qingyuan, Zhaoqing, and Jiangmen were identified as H. elachista, marking the first report of H. elachista in Guangdong Province.