Races, biovars and resistance mechanisms of Ralstonia solanacearum isolates in potato crops (Solanum tuberosum L.) in Nicaragua

Abstract

Potato (Solanum tuberosum L.) is the fourth crop grown in more than one hundred countries and the third most important food crop in the world in terms of human consumption, after rice and wheat, it is a staple food for developed countries such as Europe and USA. This crop is affected by phytosanitary problems, in which Ralstonia solanacearum stands out. The objective of this study was to identify by phenotypic test, resistance mechanisms of the bacterium Ralstonia solanacearum, isolated from the potato crop (S. tuberosum L.). The collection of samples was carried out on farms in the Miraflor and Tisey nature reserve in the department of Estelí. The isolation of the bacteria from plant tissue by means of the bacterial flux test and the soil samples were subjected to the serial dilution method. The identification of biovars was carried out with individual tests of carbohydrates and the characterization of races was by means of the infiltration test of Ralstonia solanacearum in tobacco leaves. 19 isolates with characteristics of Ralstonia solanacearum were identified that showed positive reactions to the Oxidase, Catalase and 3% KOH tests, in addition they were characterized by their aqueous growth, large, white colonies and a pink center in the tetrazolium chloride agar medium (TZC 1%), with the individual sugar test, 14 isolates of R. solanacearum were identified as biovar 1, and the remaining five as biovar 3. of R. solanacearum belongs to race 1. 12 isolates of R. solanacearum were identified with hyperproduced AmpC resistance mechanism and seven isolates cataloged as wild.