Identification of Fusarium wilt resistance gene SiRLK1 in Sesamum indicum L.

Abstract

Sesame Fusarium wilt (SFW), caused by Fusarium oxysporum f. sp. sesami (Fos), is one of the most devastating diseases affecting sesame cultivation. Deciphering the genetic control of SFW resistance is pivotal for effective disease management in sesame. An inheritance study on a cross between the highly resistant variety Yuzhi 11 and the highly susceptible accession Sp1 using a Fos pathogenicity group 1 isolate indicated that resistance was conferred by a single dominant allele. The target locus was located in a 1.24 Mb interval on chromosome 3 using a combination of cross-population association mapping and bulked segregant analysis. Fine genetic mapping further narrowed the interval between 21,350 and 21,401 kb. The locus Sindi_0812400 was identified as the SFW resistance gene and officially designated SiRLK1. This gene encodes a specific malectin/receptor-like protein kinase with three putative tandem kinase domains and is considered a kinase fusion protein. Sequence analysis revealed that a high proportion (49.44%) of variants within the locus was located within the kinase domain III, and several of which were evidently associated with the diversity in SFW response, indicating the critical role of kinase domain III in expression of disease resistance. These findings provide valuable information for further functional analysis of SFW resistance genes and marker-assisted resistance breeding in sesame.