Large-Scale Screening and Function Analysis of Rhizoctonia solani Effectors Targeting Rice Chloroplasts

Rice sheath blight (RSB), caused byRhizoctonia solani, is a major economic threat to global rice crops. The genome of R. solani contains over 103 potential effectors, with most functions still unknown. Previous studies show that chloroplast plays a crucial role in RSB resistance. However, whether R. solani effectors target plant chloroplasts to promote the pathogen infection remains unclear. This study leveraged four RSB-resistant chloroplast proteins to identify five interacting secreted proteins from a 430-protein R. solani yeast library. These proteins, which localize to rice chloroplasts, were shown to cause cell death in Nicotiana benthamiana and rice protoplasts, suggesting that they potentially influence host cellular processes by targeting chloroplasts. Bioinformatic analysis indicates that these five putative effectors almost all contained conserved structures related to pathogenicity. This study provides a novel method for screening specific functional effectors and facilitates the further study of the pathogenic mechanisms of R. solani.