ENDOPHYTIC BACTERIAL FLORA IN SOLANUM TUBEROSUM AND ITS SIGNIFICANCE IN BACTERIAL RING ROT DIAGNOSIS

Abstract

The aerobic endophytic bacterial population in "healthy" potato plants was found to vary from fewer than 1 × 10³ to 4.2 × 10⁷ cells/cm³ of stem tissue and from 0 to 1.6 × 10⁴ cells/cm³ in tubers. No significant correlation was found between the bacterial population in stems and tubers of the same plant, nor was there a significant difference in the bacterial populations of virus-free plants when compared with PVX-infected plants. Strains of Micrococcus, Pseudomonas, Bacillus, Flavobacterium, Xanthomonas, Agrobacterium, and coryneforms were isolated in addition to several isolates that could not be identified. All isolates were nonpathogenic, including the coryneforms, some of which were morphologically indistinguishable from Corynebacterium sepedonicum but which were biochemically different.