Diversity of Secretion System Apparatus in Tomato Wilt Causing Ralstonia solanacearum Strains: a Comparative Analysis Using in-silico Approach

Ralstonia solanacearum (Rs) species is the leading cause of bacterial wilt disease in a wide range of host plants worldwide. In the present study, secretion system analysis of five tomato pathogenic Rs strains was carried out in-silico . This paper describes a new protocol to identify the secretion system components i.e. SSCs (T1SS-T6SS, Flg, T4P, and Tad-Tat). A total of 865 SSCs were identified using the new protocol. Contributions of SSCs into core-secretion system apparatus (i.e. SSA) were also studied. Synteny was discovered among the secretion system apparatus (SSA) where relative frequency of SSCs to core-SSA is high (>20%) which includes T1SS, T2SS, T5SS, T4P, and Tad-Tat, but excludes T3SS, T4SS, and Flg. To the best of our knowledge, this is the first report indicating that during the evolution of Rs , most of the secretion system apparatus (T1SS, T2SS, T5SS, T4P, and Tad-Tat) were highly conserved and came from a single ancestor, while T3SS and T6SS may have arrived later, probably from horizontal gene transfer.