ScLRR Identified From BSR-seq Inhibits Sugarcane Yellow Leaf Virus Accumulation by Interacting With Its Coat Protein in the Nucleus.

Sugarcane yellow leaf disease, primarily caused by aphids-transmitted sugarcane yellow leaf virus (SCYLV), poses a major threat to sugarcane production. The complex interactions among sugarcane, SCYLV, and aphids render phenotype-based breeding inefficient for improving disease resistance. In this study, an F1 -population derived from a cross between the highly susceptible Saccharum spp. hybrids YT93-159 and the highly resistant XTT22 were evaluated for SCYLV resistance. Thirty resistant and 20 susceptible F1 -individuals were selected for bulked segregant RNA-seq (BSR-seq). A total of 276.53 Gb of clean data were generated, and 22 774 single nucleotide polymorphisms (SNPs) were identified. The top five sites with the highest ΔSNP-index values above the threshold were selected from the 108 candidate regions identified by linkage analysis of genotype and phenotype. Gene annotation of these associated regions yielded 1090 candidate genes, 17 of which encoded proteins containing multiple leucine-rich repeat (LRR) domains. One candidate gene encoding a protein containing 13 LRR domains was cloned and designed ScLRR. The ScLRR protein interacts with the SCYLV coat protein (SCYLV-CP) in the nucleus. Furthermore, we established a method for simultaneous ScLRR overexpression and SCYLV inoculation in sugarcane roots mediated by Agrobacterium rhizogenes strain K599. Overexpression of ScLRR significantly reduced SCYLV accumulation in both sugarcane and Nicotiana benthamiana. This study provides key genetic resources and theoretical foundations for understanding the molecular mechanisms and precision breeding of sugarcane resistance to SCYLV.