Overexpression of OsPGIPI Enhances Rice Resistance to Sheath Blight

摘要

Rice sheath blight (SB), caused by necrotrophic pathogen Rhizoctonia solani. is one of the most destructive rice diseases, and no major resistance genes are available. Polygalacturonase-inhibiting proteins (PGIP) are extracellular leucine-rich repeatproteins and play important roles in plant defense against different pathogenic fungi by counteracting secreted fungal polygalacturonases (PG). However, the role of PGIP in conferring resistance to rice SB remains to be thoroughly investigated. Here, weshowed that OsPGIPl is capable of inhibiting PG derived from R. solani. Our real-time reverse-transcription polymerase chain reaction results indicated that resistant rice 'YSBR1' and 'Jasmine 85' express significantly higher levels of OsPGIPl than susceptible 'Lemont'. Our results also showthat OsPGIPl is most highly expressed at the late tillering stage in the sheath of YSBR1, coinciding with the critical stage of SB development in field. More importantly, the OsPGIPl level is highly elevated by inoculation with R. solani in resistant cultivars but not in susceptible Lemont Overexpression of OsPGIPl significantly increased rice resistance to SB and inhibited tissue degradation caused by R. solani-secreted PG. Furthermore, OsPGIPl overexpression did not affect rice agronomic traits or yield components. Together, our results not only demonstrate the important role of OsPGIPl in combatting the rice SB disease but also provide a new avenue to the improvement of rice SB resistance by manipulating an endogenous gene.