Molecular Diagnostic Tool for Specific Identification of Ralstonia solanacearum through SCAR Marker

One hundred and fourteen isolates of Ralstonia solanacearum, collected from wilt affected chilli, eggplant and tomato fields of Karnataka and Goa states in India were used for study. The identification and confirmation of all isolates were done based on cultural characteristics, pathogenicity test and PCR amplification of 16S rDNA region. Among collected isolates, randomly 20 isolates were taken for RAPD analysis. Two specific RAPD markers were identified. Two species specific SCAR primers (RS-1, RS-2) were designed. The primer RS-1 amplified FRFR FR a single product of 920 bp with DNA samples from all R. solanacearum isolates. On the other hand, RS-2 _FR primer amplified an additional band along with expected 900 bp, hence only RS-1 _FR considered as suitable SCAR marker. The specificity of the primer was confirmed by absence of amplified products with DNA from other bacterial species. Generated RAPD amplicon profile from 20 different isolates was used for genotypic diversity analysis using NTSYSpc 2.02j software. Very high level of genome variability was noticed among the isolates. Study provided a rapid identification method that allows an accurate detection of R. solanacearum and expected to be useful for disease diagnosis in early stage of bacterial infection.