Sheath blight (ShB), caused by the necrotrophic fungus Rhizoctonia solani, is one of the most serious rice diseases worldwide. In this study, we successfully grafted salicylic acid (SA) onto mesoporous silica nanoparticles through an amide-bond coupling method, forming functionalized MSN-SA nanoparticles. Physicochemical characterization showed that the MSN-SA nanoparticles were spherical, with an average particle size of approximately 30 nm and an SA loading rate of around 7.21%. The assessment of ShB resistance revealed that both SA and MSN-OH treatments were capable of inducing resistance to a certain extent. When SA and MSN-OH were applied in combination, the resistance was further augmented, indicating an additive effect between them. Intriguingly, MSN-SA treatment (50% in Lemont) exhibited a higher and more durable control efficacy compared with SA + MSN-OH treatment (33%). Moreover, field experiments demonstrated that the MSN-SA was safe for rice, and under severe disease conditions, it could recover 16.7% of the yield loss, thus highlighting its substantial application value. Further transcriptome analysis and physicochemical assays suggested that MSN-SA released SA in a slow and continuous manner, thus persistently activating the immune response, and that MSN-SA integrated the effects of SA and MSN-OH, thereby enhancing the ShB resistance. Altogether, our results provide new perspectives and a novel nanomaterial-based immune elicitor for the green control of ShB.

Grain chalkiness is an undesirable trait that significantly compromises rice quality, attracting considerable attention from both consumers and breeders. In this study, we characterized the role of the autophagy-related gene OsATG4b in rice grain development. OsATG4b was predominantly expressed in the endosperm. Compared with wild-type plants, OsATG4b-overexpressing lines exhibited significantly reduced grain chalkiness, whereas OsATG4b knockout mutants displayed a marked increase in chalkiness. Importantly, OsATG4b had no significant effect on other major agronomic traits. Ultrastructure analysis of the endosperm and evaluation of seed storage components revealed that the chalky endosperm in OsATG4b Knockout mutants contained loosely packed starch granules, aberrant protein bodies, and reduced levels of seed storage proteins. Furthermore, gene expression analysis indicated that OsATG4b regulates the expression of genes involved in storage protein biosynthesis. Together, these findings demonstrate that OsATG4b plays a critical regulatory role in determining grain chalkiness in rice.

Grain chalkiness is an undesirable trait that significantly compromises rice quality, attracting considerable attention from both consumers and breeders. In this study, we characterized the role of the autophagy-related gene OsATG4b in rice grain development. OsATG4b was predominantly expressed in the endosperm. Compared with wild-type plants, OsATG4b-overexpressing lines exhibited significantly reduced grain chalkiness, whereas OsATG4b knockout mutants displayed a marked increase in chalkiness. Importantly, OsATG4b had no significant effect on other major agronomic traits. Ultrastructure analysis of the endosperm and evaluation of seed storage components revealed that the chalky endosperm in osatg4b mutants contained loosely packed starch granules, aberrant protein bodies, and reduced levels of seed storage proteins. Furthermore, gene expression analysis indicated that OsATG4b regulates the expression of genes involved in storage protein biosynthesis. Together, these findings demonstrate that OsATG4b plays a critical regulatory role in determining grain chalkiness in rice.