Races and Biovar Characterization of Ralstonia solanacearum Causing Bacterial Wilt Disease of Potato

Ralstonia solanacearum, the causative agent of brown rot/bacterial wilt, is a major cause of severe potato illnesses in many impoverished nations located in tropical and subtropical regions of the world. When it occurs, the disease is to blame for significant losses to the potato industry. The illness has the potential to completely destroy a crop and stop using a piece of land for potato cultivation for a number of years. A survey was carried out to investigate the extent of Ralstonia solanacearum-caused bacterial wilt of potato crops in important potato-growing talukas in the Banaskantha district of Gujarat, India, including Deesa, Dantiwada, Palanpur, and Amirgadh. The frequency of bacterial wilt disease in potatoes is rather low in this region. Four talukas were utilised to identify ten isolates (RsSt1 to RsSt10) of R. solanacearum, which were then used to determine the biovar and race. Gram-negative rod-shaped cells were present in the isolates of R. solanacearum. On TZC agar medium, these isolates developed colonies that were creamy or dull white in colour with a hint of pink or red in the centre. The oxidation of disaccharides (sucrose, lactose, maltose) and sugar alcohols (manitol, sorbitol, and dulcitol) by R. solanacearum isolates was used to determine the biovar characteristics. This revealed that, of the ten isolates, eight were classified as bv2, and the two remaining isolates (RsSt5 and RsSt7) belonged to bv2T. The pathogenicity test conducted on tobacco, tomato, and brinjal allowed for the race identification of R. solanacearum isolates, which were classified as race 3 due to their limited host range and ability to exclusively elicit wilt symptoms in potatoes and tomatoes. As a result, Races 3 and bv2 and bv2T were represented among the R. solanacearum isolates that caused bacterial wilt of potatoes in the Banaskantha district.