Population changes of gusA-marked Ralstonia solanacearum in the soil under two moisture and temperature conditions

Abstract

The survival of the pathogenic gusA-labeled R. solanacearum strain JCA in three soil types at different moisture regimes was investigated. The three tomato-dedicated soils (Lipa clay loam, Bago sandy clay, and sandy loam from Mt. Banahaw) were initially found not to have microorganisms with GUS activity as detected on Kelman's agar (without glucose) containing 100 μg mL-1 each of nitrofurantoin and spectinomycin and 40 μg mL-1 5-bromo-4-chloro-3-indolyl-β-D;Glucuronide (X-glc). The population of the labeled pathogen was adversely affected by low moisture in all soil types used and also most probably by the low clay content of Mt. Banahaw soil. The effect of temperature on the survival of the pathogen was also investigated at two temperature conditions (25 C and 35 C) in Lipa Clay loam. The gusA-labeled R. solanacearum population was slightly reduced at both soil temperatures of 25 C and 35 C, although it was slightly higher in the latter than in the former. The results showed that marking R. solanacearum with gusA and double antibiotics made it possible for the bacterium to be traced reliably, efficiently and with considerable selectivity in three soil types under natural conditions.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

161-169

Document Type

Article

Subject

gusA, Ralstonia solanacearum, Soil moisture content, Soil temperature, Tomato bacterial wilt

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