Control of Rice Sheath Blight by Combining Susceptible Genes Editing and Nano‐Immune Inducer Spraying

Sheath blight (ShB), caused by the necrotrophic fungus Rhizoctonia solani, is one of the serious diseases in rice worldwide (Nizamani et al. 2025). Rice resistance to ShB is controlled by polygenes, each with minor effects on resistance, and to date very few resistance genes with breeding potential have been identified, which heavily hinders the progress on developing ShB resistant varieties (Gao et al. 2021; Wang, Liu, et al. 2025). Currently, the ShB disease management has predominantly relied on synthetic chemical fungicides such as thifluzamide (THF) (Wang, Liu, et al. 2025). With the rapid advancement of genome editing technologies, modifying susceptibility genes has become an increasingly prominent approach for developing disease-resistant crop varieties (Koseoglou et al. 2022). Regarding rice ShB disease, several susceptibility genes, such as OsSGR, DEP1 and Oserf7, have been reported (Xie et al. 2024, 2025; Zhu et al. 2025). However, although the knockout of these genes enhanced ShB resistance, most caused significant reductions in grain yield, (Zhu et al. 2025). Previously, we reported that Oserf7 negatively regulates ShB resistance by suppressing the biosynthesis of plant phytoalexin, and importantly, the Oserf7 line showed a similar grain yield as the WT, suggesting its important potential in rice breeding (Xie et al. 2025). Here, we report another ShB susceptible gene, PPS-b, which encodes phosphoinositide-binding protein. In total, PPS-b was found to have comparable expression levels among different rice tissues and developmental stages, (Figure S1a). During R. solani infection, the expression of PPS-b was slightly suppressed (Figure S1b), suggesting its potential role in rice—R. solani interaction. The PPS-b protein mainly localized on the cell membrane (Figure 1a). To determine the function of PPS-b in ShB resistance, we developed two PPS-b overexpression lines (PPS-bOE-1 and -2) and knockout lines (pps-b-1 and -2), respectively (Figure S2a; Figure 1b). After inoculation with R. solani, we found that pps-b lines significantly enhanced resistance to ShB, whereas PPS-bOE lines reduced resistance compared with the wildtype (WT) control (Figure 1c–e; Figure S2b,c), demonstrating a susceptible role of PPS-b in response to R. solani infection. In order to analyse its susceptible mechanism, we compared the transcriptomic profiles of WT and pps-b-1 lines after R. solani infection. KEGG analysis and GO enrichment showed that PPS-b negatively regulates ShB resistance mainly by suppressing salicylic acid (SA)-mediated immune signalling (Figure 1f; Figure S3). To further evaluate the potential of the pps-b line in rice breeding, we compared its yield-associated traits with those of the WT in the field (Figure S4), and found that no significant differences were observed in seed setting ratio (SSR), 1000-grain weight (TGW), grain number per panicle (GNP), productive panicle number per plant (PPNP) and grain yield per plant (GYP) calculated by the former 4 yield-associated components. In addition, we did not find significant differences in plant height and heading date between the WT and pps-b lines (Figure 1e). Together, these data confirm that the knockout of the PPS-b gene has potential in rice breeding against ShB disease. In addition to identifying valuable genes for resistance breeding, we developed a nano-immune inducer (MSN-SA) that effectively suppresses ShB disease by activating SA-mediated defence signalling pathways and enhancing cell wall fortification (Wang, Chen, et al. 2025). Therefore, we would like to compare the effects of Oserf7 and pps-b lines and of MSN-SA and fungicide THF treatments on controlling ShB disease. In a field inoculation assay using ‘0–9’ disease severity rating scale (Xie et al. 2024), we found that the disease scores of WT reached 7.27 ± 0.25, significantly higher than those of other treatments, and the disease scores (2.57 ± 0.09) of WT treated by THF were the lowest among all treatments (Figure 1g–j). Comparatively, the disease scores of Oserf7 (6.03 ± 0.28), pps-b (6.15 ± 0.20), WT + MSN-SA (5.74 ± 0.45) (means WT treated by MSN-SA) and pps-b + MSN-SA (5.40 ± 0.24) lines showed a similar disease severity and all significantly higher than that of Oserf7 + MSN-SA line (4.07 ± 0.32) (Figure 1j), indicating a better effect of ‘Oserf7 + MSN-SA’ combination on reducing ShB disease. Furthermore, we observed that the ‘Oserf7 + MSN-SA’ combination reduced ShB severity scores (7.27 − 4.07 = 3.3) significantly more than the calculated additive effect (1.24 + 1.53 = 2.77) of individual Oserf7 (7.27 − 6.03 = 1.24) and MSN-SA treatment (7.27 − 5.74 = 1.53) in WT plants. In contrast, no such synergistic effect was observed in ‘pps-b + MSN-SA’ combination, indicating specific synergy between Oserf7 and MSN-SA in suppressing ShB. The ‘Oserf7 + MSN-SA’ combination had achieved 68.5% disease reduction efficacy relative to the conventional chemical fungicide THF (4.67) (Figure 1j). In growth chamber trials using detached tiller inoculation assay, the ‘Oserf7 + MSN-SA’ combination demonstrated superior suppression of lesion development, reducing a mean lesion length by 10.2 cm, which reached the efficacy of 78.5% of fungicide THF-treated control (reduced lesion length by 13.0 cm) (Figure 1k–n). According to the resistance mechanisms of Oserf7, pps-b and MSN-SA against ShB, we then compared the transcription levels of critical genes associated with SA-mediated defence signalling pathway and phytoalexin biosynthesis by RT-qPCR as well as the transcriptomic profiles by RNA-seq (Figure 1f, Figure S5). We found that both SA-mediated defence signalling and phytoalexin biosynthesis were strongly strengthened in ‘Oserf7 + MSN-SA’ combination (Figure S5a); while in ‘pps-b + MSN-SA’ combination, a clearly overlapped defence response on SA signalling pathway were observed (Figure 1f, Figure S5b). These data accounted for the positively synergistic effect of ‘Oserf7 + MSN-SA’ on controlling ShB. To further evaluate the effect of different treatments on GYP, we measured PPNP, GNP, TGW and SSR for each plot in the field. We found that, except for Oserf7 lines, all treatments showed a comparable PPNP and GNP (Figure S6), indicating minimal influence of ShB disease on these two yield components. The Oserf7 line displayed a slightly higher PPNP but lower GNP compared with WT, and ultimately showed similar GYP as the WT, which is consistent with the previous finding (Xie et al. 2025). Comparatively, TGW was affected mostly by the ShB, and then was SSR (Figure 1o,p), which were responsible for the difference of GYP among treatments (Figure 1q,r). The WT plants treated by THF showed the highest GYP (22.41 ± 1.68 g), which were significantly higher than other treatments except for the Oserf7 line treated by MSN-SA (21.76 ± 1.06 g). Relative to the GYP protection (6.31 g) conferred by THF fungicide (derived from the GYP of WT-THF minus the GYP of WT), the ‘Oserf7 + MSN-SA’ combination treatment exhibited comparable protective effects, restoring 5.66 g of GYP, achieving 89.7% efficacy of THF. Collectively, these data indicate a promising sustainable strategy of ‘Oserf7 + MSN-SA’ for both ShB management and yield maintenance under field conditions. In summary, our finding provides an eco-friendly innovative approach by combining susceptible gene editing and the treatment of immune inducer to sustainable management of ShB disease, which will not only accelerate the progress on developing more positively synergistic combinations from susceptible genes and immune inducers to control ShB disease, but also provide a novel idea for green managing other diseases in crops. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Figures S1–S6. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. 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