Characterization of Ralstonia solanacearum phylotype 1 and reduction of its population in biofumigated soil
2012
Belendres, M.A.O. | Justo, V.P. | Pathania, N. | Trevorrow, P. | Dela Cueva, F.M.
Bacterial wilt, caused by Ralstonia solanacearum, is a widespread disease in the Philippines and common in regions were solanaceous and high valued crops are grown. Knowledge of the pathogen is well documented but is very interesting because of its 'species-complexity'. This includes groupings based on races, phylotypes, and biovars in differentiate strains. In this study both phenotypic and genotypic methods were used to characterize R. solanacearum isolates belonging to Phytotype 1 (Asia group) in Bukidnon. Rep-PCR genomic fingerprinting (Rep-, ERIC-, and BOX-PCR) that uses DNA primers complimentary to naturally occurring, highly conserved, repetitive sequences, and are present in multiple copies in the genome in most gram-negative bacteria was employed to classify R. solanacearum. Cluster analysis by UPGMA revealed 3 rep-PCR groupings based on isolates location, aggressiveness and host at 70% similarity coefficient. Appropriate and effective management strategies for this disease is highly warranted. Among the methods included in the integrated pest management (IPM) of bacterial wilt is biofumigation, a process that suppresses soil-born pests and pathogens by naturally occurring biocides released in soil when tissues of plants decomposed. Biofumigant plants are those that have the ability to produce high levels of glucosinates that are converted to isothiocyanates (ITCs) which becomes toxic to soil-borne pathogens. Instead of the common brassica plants e.g. radish, this study explored the use of sunflower, commonly available plant, as alternative biofumigant. The suppression achieved in this study was very encouraging. Initial results showed decrease in bacterial population in biofumigated soil, both in sunflower and radish treatments, against the uncreated (non-biofumigated) soil. There were significant decrease also in the incidence and severity of the disease on tomato cv. yellow plum plants in biofumigated soils compared to non-biofumigated soil.
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