Characterization and genetic diversity of Ralstonia solanacearum causing brown rot disease of potato

The genetic diversity among Indian strains of Ralstonia solanacearum, causal agent of bacterial wilt of potato, was assessed by repetitive sequence-based polymerase chain reaction (rep- PCR) method. Sixty three strains of R. solanacearum isolated from potato, which were collected from different states of India viz. Uttarakhand, Meghalaya, West Bengal, Himachal Pradesh, Orissa, and Karnataka under different agro-climatic regions. Characterization of races and biovars of these strains of R. solanacearum was done and two races (race 1 and race 3) and four biovars (bv 1, bv 2, bv2T and bv3) were recorded from potato. Genetic diversity these 63 strains of R. solanacearum was done by using rep-PCR (BOX, ERIC and REP- PCR primers). The strains of R. solanacearum formed 42 clusters (group) at 70% similarity coefficient. The strains of R. solanacearum isolated from Uttarakhand formed group 1- 5, 8-9 and group 23, from Meghalaya formed groups 6-7, 10-20, 24, 38-39, from West Bengal formed groups 25 and 27, from Odisha formed groups 26, 35- 37 and 40- 42, from Karnataka formed groups 22, 30-34 and from Himachal Pradesh formed group 21, 28-29. Maximum genetic diversity in strains of R. solanacearum was found, which were collected from Shilong (Meghalaya) and clustered in 18 clusters followed by strains collected from Nainital, hill areas (Uttarakhand) divided into 8 groups. However, the strains collected from plains i.e. Karanataka belongs to R1/bv3 cluster in one group, likewise the strains of Odisha R3/bv2 & 2T clustered in separate group and strains from West Bengal R1/bv3 clustered in one group. Thus the study indicated the existence of wide range of genetic diversity among the Indian strains of R. solanacearum causing brown rot of potato.