Mapping and candidate gene screening of tomato Cladosporium fulvum- resistant gene Cf-19 , based on high-throughput sequencing technology

摘要

Background Tomato leaf mold is a common disease in tomato cultivation. This disease is caused by Cladosporium fulvum , which has many physiological races and differentiates rapidly. Cf genes confer resistance to C. fulvum , and the C. fulvum -tomato pathosystem is a model for the study of gene-for-gene interactions. Plants carrying the Cf-19 gene show effective resistance to C. fulvum in the field, and can be used in breeding and resistance mechanism studies as new resistant materials. In this study, we used F₂ bulk specific-locus amplified fragment sequencing (SLAF-seq) and parental resequencing methods to locate and characterize the Cf-19 gene. Results A total of 4108 Diff_markers and three association regions were found in association analysis. A 2.14-Mb region containing seven Cf -type genes was identified in further analysis based on data from SLAF-seq and parental resequencing. Two candidate genes, Solyc01g006550.2.1 and Solyc01g005870.1.1, were screened out by quantitative real-time PCR (qRT-PCR) analysis. Sequence analysis showed that Solyc01g006550.2.1 (an allelic locus of Cf-0 ) in CGN18423 was a novel homologue of the Cladosporium resistance gene Cf-9 ( Hcr9s ) in the Cf-4/9 locus. The marker P7, which cosegregated with the resistant trait, was developed based on sequence mutation of the Solyc01g006550.2.1 locus in CGN18423. Conclusions The Cf-19 gene was mapped to the short arm of chromosome 1. The candidate genes Solyc01g006550.2.1 and Solyc01g005870.1.1 showed related amino acid sequence structures and expression patterns. Solyc01g006550.2.1 had a close evolutionary relationship with the functional Hcr9 members Cf-4 and Cf-9 , and was very different from non-functional members. The results from this study will facilitate the breeding of cultivars carrying the Cf-19 gene and provide a basis for further gene cloning, resistance gene evolution and plant resistance mechanism studies.