Rice sheath blight, caused by Rhizoctonia solani, is one of the three major diseases of rice, posing a serious threat to rice production. Currently, the sustainable management of rice sheath blight remains constrained by both the limited availability of resistant germplasm and the incomplete understanding of molecular defense mechanisms, representing critical barriers to effective disease control. Although sugar transport proteins (STPs) have been implicated in plant immunity, their functions in rice resistance against R. solani remain unclear. This study demonstrated that R. solani inoculation significantly induced the expression of rice STP genes. Through integrated bioinformatics analysis, protein structure prediction, subcellular localization, and functional validation, we revealed that: OsSTP4 and OsSTP14, as stably expressed alkaline transmembrane proteins, exhibited broad substrate specificity for hexose transport (including glucose, fructose, and galactose), while OsSTP26 specifically transported glucose due to its structural instability; three-dimensional structure modeling identified a unique acidic amino acid cluster in the extracellular domain of STP4, suggesting its potential role in substrate recognition via electrostatic interactions; functional validation showed that OsSTP4-silenced plants exhibited enhanced susceptibility to sheath blight, while OsSTP26 knockout mutants displayed less susceptible to sheath blight compared to wild-type control. These findings unveil the functional antagonism between OsSTP4 and OsSTP26 in sheath blight resistance, elucidating their molecular basis in this regulatory process and providing theoretical insights into the functional heterogeneity of the STP family members.

Late blight, caused by Phytophthora infestans, is one of the most devastating diseases affecting global potato production. Identifying disease-resistant genes and developing resistant potato varieties are key strategies for its management. Xyloglucan endotransglucosylase/hydrolases (XTHs), as pivotal cell wall-modifying enzymes, play crucial roles in regulating plant growth, development, and abiotic stress responses. However, the specific role of XTHs in plant defense against pathogens remains unclear. In this study, we identified a xyloglucan endotransglucosylase/hydrolase, StXTH9, in potato. Transcriptome analysis and reverse transcription-quantitative real-time PCR (RT-qPCR) validation revealed that P. infestans infection significantly upregulated StXTH9 expression. Subcellular localization showed that StXTH9 targets multiple compartments including the cell wall, plasma membrane, and nucleus. Through Agrobacterium-mediated genetic transformation, we successfully generated StXTH9 gene-edited mutants and overexpression lines in potato (Solanum tuberosum), as well as StXTH9-overexpressing Nicotiana benthamiana plants. Disease resistance phenotyping demonstrated that StXTH9 mutants exhibited significantly enhanced resistance to P. infestans, whereas StXTH9-overexpressing plants showed increased susceptibility. Additionally, StXTH9 negatively regulated pattern-triggered immunity (PTI) immune responses by inhibiting flg22-induced reactive oxygen species (ROS) burst and MAPK activation, as well as INF1-induced cell necrosis. In conclusion, StXTH9 functions as a negative immune regulator in potato resistance to P. infestans, providing new theoretical insights and a promising candidate gene for molecular breeding of disease-resistant potato varieties.

Oidium heveae is an incompatible pathogen of Arabidopsis Col-0, and triggers disease resistance in Arabidopsis in an EDS1 (ENHANCED DISEASE SUSCEPTIBILITY 1) and PAD4 (PHYTOALEXIN DEFICIENT 4) dependent manner, suggesting that TIR-NB-LRR (TOLL INTERLEUKIN 1 RECEPTOR, NUCLEOTIDE-BINDING, LEUCINE-RICH REPEAT) genes may involve in the disease resistance against O. heveae. In this study, the differentially expressed TIR-NB-LRR genes targeting O. heveae were screened, and the expression of WRR4C (WHITE RUST RESISTANCE 4C) gene was found to up-regulated induced by O. heveae. Through inoculation assay, O. heveae was observed to develop dense hyphal network and a few conidia in two wrr4c single mutants, and triggered significantly decreased defense responses including cell death, callose deposition and PR1 (Pathogenesis Related 1) gene expression, indicating that WRR4C positively regulated the disease resistance of Arabidopsis against the powdery mildew of Hevea brasiliensis. However, WRR4C gene did not participate in the cell pre-penetration resistance to O. heveae, and the expression of WRR4C reached to the highest level at 48 hours post inoculation, suggesting that WRR4C genes was mainly involved in the cell post-penetration resistance of Arabidopsis to O. heveae. In addition, we found WRR4C also positively regulated the disease resistance against Erysiphe polygoni in Arabidopsis.