Rice sheath blight (RSB), caused by the pathogenic fungus Rhizoctonia solani, poses a significant threat to global food security. The defense mechanisms employed by rice against RSB are not well understood. In our study, we analyzed the interactions between rice and R. solani by comparing the phenotypic changes, ROS content, and metabolite variations in both tolerant and susceptible rice varieties during the early stages of fungal infection. Notably, there were distinct phenotypic differences in the response to R. solani between the tolerant cultivar Zhengdao22 (ZD) and the susceptible cultivar Xinzhi No.1 (XZ). We observed that the activities of five defense-related enzymes in both tolerant and susceptible cultivars changed dynamically from 0 to 72 h post-infection with R. solani. In particular, the activities of superoxide dismutase and peroxidase were closely associated with resistance to RSB. Metabolomic analysis revealed 825 differentially accumulated metabolites (DAMs) between the tolerant and susceptible varieties, with 493 DAMs responding to R. solani infection. Among these, lipids and lipid-like molecules, organic oxygen compounds, phenylpropanoids and polyketides, organoheterocyclic compounds, and organic acids and their derivatives were the most significantly enriched. One DAM, P-coumaraldehyde, which responded to R. solani infection, was found to effectively inhibit the growth of R. solani, Magnaporthe grisea, and Ustilaginoidea virens. Additionally, multiple metabolic pathways, including amino acid metabolism, carbohydrate metabolism, metabolism of cofactors and vitamins, and metabolism of terpenoids and polyketides, are likely involved in RSB resistance. Our research provides valuable insights into the molecular mechanisms underlying the interaction between rice and R. solani.

To elucidate the molecular mechanisms underlying salt tolerance in rice (Oryza sativa L.), this study investigated differential transcriptional responses during the tillering stage. Salt-tolerant (N14) and salt-sensitive (N6) varieties were subjected to 0.3% and 0.6% NaCl treatments for 72 h, and their transcriptomes were analyzed via RNA-Seq. The results revealed distinct response strategies: 372 differentially expressed genes (DEGs) were identified in N14 and 393 in N6, with only 17 genes responding similarly. Gene Ontology (GO) analysis showed the tolerant N14 activated protein phosphorylation and lipid transport, primarily in the membrane and extracellular regions (e.g., ATP binding), whereas the sensitive N6 activated photosynthesis and protein folding, localized to chloroplasts and peroxisomes. KEGG analysis highlighted the activation of “Plant-pathogen interaction” in N14 versus “Metabolic pathways” in N6. Differential transcription factor activation was also observed, with N14 mobilizing 52 TFs (mainly WRKY and MYB) and N6 mobilizing 36 TFs (mainly MYB and b-ZIP). This study demonstrates that N14 and N6 utilize significantly different molecular pathways to cope with salinity, providing a crucial theoretical foundation for identifying novel salt tolerance genes and developing molecular breeding strategies.

Rice, a staple food for billions around the globe, is cultivated in numerous forms. Among them, soft rice is well known, which is characterized by its tender, creamy consistency and desirable texture. In this study, we examined the physicochemical properties and fine structure of starch from two soft rice varieties, Jinong Xiangruan 1 and DGR1, cultivated in different regions in China (Baodi District, Tianjin City; Liaoning Province; and Fengyang City, Anhui Province). The aim was to understand how amylopectin content (AC) influences rice quality. This research aims to bridge the knowledge gap regarding the role of amylopectin in determining rice’s adhesive consistency and viscosity. Significant regional differences were observed in yield components such as the number of grains per panicle, seed setting rates and 1000-grain weight, with Liaoning generally showing higher performance metrics compared to other regions. Physicochemical analysis highlighted that though glue consistency and taste values showed little regional variation, AC significantly influenced rice hardness and viscosity. Rapid Visco Analyzer (RVA) profile analysis further demonstrated distinct differences in viscosity characteristics, underscoring the regional impacts on starch behavior. Additionally, molecular weight distribution and amylopectin chain length analysis, conducted via SEC-MALLS-RI and ICS ion chromatography, revealed notable differences in starch composition across varieties and locations. The findings suggest that environmental conditions play a crucial role in defining starch characteristics and, consequently, the eating quality of rice. This provides valuable insights for breeding high-quality japonica rice with broad adaptability.