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

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 domainⅢ,and several of which were evidently associated with the diversity in SFW response,indicating the critical role of kinase domainⅢin expression of disease resistance.These findings provide valuable information for further functional analysis of SFW resistance genes and marker-assisted resistance breeding in sesame.

Production profile and comparison analysis of main toxin components of Fusarium oxysporum f.sp.sesami isolates with different pathogenicity levels

Fusarium wilt is a common fungal disease in sesame caused by Fusarium oxysporum f.sp.sesami(FOS).To determine the toxin production profiles of the FOS isolates with different pathogenicity levels under various culture conditions,we assessed the content variation of fusaric acid(FA)and 9,10-dehydrofusaric acid(9,10-DFA)produced by the four representative FOS isolates.Results indicated that the concentration of FA reached to a maximum of 2848.66μg/mL in Czapek medium,while 9,10-DFA was mainly produced in Richard and Lowcarbon Richard medium.The concentration of 9,10-DFA on Richard culture medium varied from 0μg/mL to 716.89μg/mL.Of the five culture media used in this study,Czapek culture medium was the most conductive to produce FA.FA production was significantly affected by culture medium,culture time,and their interactions.Results suggest that there is no correlation between toxin production and pathogenicity level of FOS isolates.These findings provide key information for the mechanism analysis of FOS-sesame interaction and pathogen control.