Assessment of resistance status of some tomato genotypes to bacterial wilt disease and evaluation of SNP marker (LEOH19) for selection of BW resistant gene

Abstract

Marker assisted selection (MAS) has become very important and useful in selection of disease resistance genes in crop plants. Tomato, Solanum lycopersicum, is one of the most important vegetables worldwide but its production is being affected by pests and diseases, one of which is bacterial wilt caused by Ralstonia solanacearum. In endemic areas, the disease constitutes up to 100% yield loss. A-Two-season completely randomized design (CRD) experimental trial was conducted to assess the resistance status of forty (40) tomato genotypes. The results showed variations in resistance status, from highly resistance to highly susceptible. DNA concentrations from the assessed genotypes ranged between 14.46 and1430.52 ng/ul. Single Nucleotide Polymorphism (SNP) marker, LEOH19, was evaluated on the forty tomato genotypes for the identification of bw-gene that confers resistance to R. solanacearum. Genomic DNA was amplified using the primer sequence; (forward primer; 5´- AAGGCTCAGAAAGGGTCCAT-3´, reverse primer; 5´- GAGTTCATCAACACATCACACA-3´). The primer pairs produced amplification at 300 bp in 35 genotypes. After digestion, the product produced 300 bp in 33 genotypes. In screenhouse study, AVTO9803, AVTO0201, Tomachiva and Eyetom were found highly resistant and could be considered good materials in grafting and breeding programme for bacterial wilt resistance development. The results indicated that the primer amplified the specific sequence of the bw-gene locus in both the resistant and susceptible alleles. LEOH19 was found to be monomorphic and produced DNA fragments in both resistant and susceptible tomato genotypes and could, therefore, not be used as a molecular marker for marker assisted selection in tomato breeding programme.

Key words: Bacterial wilt, Ralstonia solanacearum, resistance, SNP, Tomato.