Distribution of <em>Pseudomonas solanacearum</em> in the stem tissues of tomato plants with different levels of resistance to bacterial wilt.

Ten tomato cultivars, from the USA, Taiwan and French Antilles, were compared for resistance to bacterial wilt as measured by disease and pathogen population invasiveness and density in the stem at the collar and midstem regions. On the basis of disease incidence, cultivars ranked from highly susceptible to totally resistant. By contrast, no significant difference was observed in bacterial population in wilting plants, regardless of the cultivar. All symptomless plants were latently infected at the collar level. Percentage of symptomless plants with bacteria at the midstem level was significantly correlated with the degree of resistance; the more resistant, the lower the stem colonization. Restriction of Pseudomonas solanacearum invasiveness in the vascular tissues of the stem is associated with resistance properties in tomato. This observation may be useful in developing improved criteria for selecting stable resistance to the disease. [ABSTRACT FROM AUTHOR]