Effects of Colonization of the Roots of Domestic Rice (Oryza sativa L. cv. Amaroo) by Burkholderia pseudomallei

Burkholderia pseudomallei is a saprophytic bacterium that causes melioidosis and is often isolated from rice fields in Southeast Asia, where the infection incidence is high among rice field workers. The aim of this study was to investigate the relationship between this bacterium and rice through growth experiments where the effect of colonization of domestic rice (Oryza sativa L. cv Amaroo) roots by B. pseudomallei could be observed. When B. pseudomallei was exposed to surface-sterilized seeds, the growth of both the root and the aerosphere was retarded compared to that in controls. The organism was found to localize in the root hairs and endodermis of the plant. A biofilm formed around the root and root structures that were colonized. Growth experiments with a wild rice species (Oryza meridionalis) produced similar retardation of growth, while another domestic cultivar (O. sativa L. cv Koshihikari) did not show retarded growth. Here we report B. pseudomallei infection and inhibition of O. sativa L. cv Amaroo, which might provide insights into plant interactions with this important human pathogen.