Isolation and Identification of Bacteria Causing Tomato Leaf Spot in Yemen with Susceptibility of Certain Cultivars

Abstract

This study was conducted to isolate and identify the causal agent of bacterial leaf spot disease on tomato in district fields in Kla’abah, Taiz, Yemen. Twenty isolates were obtained from tometoes leaves and fruit of infected plants. Yellow, raised and shiny colonies were developed on four media ((1% Glucose nutrient agar (GNA), Nutrient dextrose agar (NDA), Sucrose peptone agar (SPA) and Yeast peptone glucose agar (YPGA)). Pathogenicity test results showed three isolates were highly virulent while three other isolates were moderately virulent. The pathovar Xanthomonas campestris pv. vesicatoria was identified according to visible characteristics of the colonies by (GNA, NDA, SPA and YPGA) media, cell shape, and physiological and biochemical characteristics (ability to grow at 35o C, production of H2S and ability to assimilate certain carbohydrates). Results revealed the ability of Xanthomonas campestris pv. vesicatoria to infect nine tomato cultivars (Roma V.f., Riogrand Gala, Tomato Maryam, Gala, Riogrand, Local-G 1oo3, on gy.A Seed, Ti 2 ar and RioGrand-Tezier) causing leaf spot at 26 – 29o C. Results also showed on Ti 2 ar, Local-G 1oo3 and Roma V.f. cultivars a decreased level of bacteria multiplication while Riogrand Gala, on gy. A Seed and Riogrand cultivars showed increased bacteria population.