Comprehensive Genome-Wide Analysis of the Receptor-like Protein Gene Family and Functional Analysis of PeRLP8 Associated with Crown Rot Resistance in Passiflora edulis

Passion fruit (<i>Passiflora edulis</i> Sims) is a Passifloraceae plant with high economic value. Crown rot caused by <i>Rhizoctonia solani</i> is a major fungal disease, which can seriously reduce the yield and quality of passion fruit. Receptor-like proteins (RLPs), which act as pathogen recognition receptors, are widely involved in plant immune responses and developmental processes. However, the role of <i>RLP</i> family members of passion fruit in resistance to crown rot remains unclear. In this study, evolutionary dynamics analysis and comprehensive genomic characterization of the <i>RLP</i> genes family were performed on passion fruit. A total of 141 <i>PeRLPs</i> in the genome of the 'Zixiang' cultivar and 79 <i>PesRLPs</i> in the genome of the 'Tainong' cultivar were identified, respectively. Evolutionary analysis showed that proximal and dispersed duplication events were the primary drivers of <i>RLP</i> family expansion. RNA-seq data and RT-qPCR analysis showed that <i>PeRLPs</i> were constitutively expressed in different tissues and induced by low temperature, JA, MeJA, and SA treatments. The <i>PeRLP8</i> gene was identified as the hub gene by RNA-seq analysis of passion fruit seedlings infected by <i>Rhizoctonia solani</i>. The expression levels of <i>PeRLP8</i> of the resistant variety <i>Passiflora maliformis</i> (LG) were significantly higher than those of the sensitive variety <i>Passiflora edulis</i> f. <i>flavicarpa</i> (HG). Transient overexpression of <i>PeRLP8</i> tobacco and passion fruit leaves enhanced the resistance to <i>Rhizoctonia solani</i>, resulting in reduced lesion areas by 52.06% and 54.17%, respectively. In addition, it can increase reactive oxygen species levels and upregulated expression of genes related to active oxygen biosynthesis and JA metabolism in passion fruit leaves. Our research provides new insights into the molecular mechanism and breeding strategy of passion fruit resistance to crown rot.