Infection Process of Burkholderia glumae in Rice Spikelets

Abstract

AbstractBurkholderia glumae, which causes bacterial panicle blight of rice (BPBR), is a well‐known pathogen. The pathogen‐induced symptoms include seedling rot, grain rot and leaf‐sheath browning in rice plants. B. glumae can incubate in rice plants as endophytes before booting stage of rice. In this study, we constructed a gfp‐labelled system of B. glumae LMG 2196 and used SEM to clarify the colonization course of B. glumae at the heading stage. New locations of B. glumae were found. The pathogens initially distributed on the surface of the glumes and colonized in the glume hairs and cells of the edge of sterile lemma, palea and lemma. The base of glume hairs was the initial position for colonization. Bacterial population raised around glume hairs, penetrated into the inner surface of the palea and lemma, and spread on the gynoecium and stamens through contact. The spreading of B. glumae among the panicles mainly occurred through the contact or friction among glumes or leaf sheaths, but the inner spread of the stamens mainly occurred through the connective tissue of anther. We also detected the differences of bacterial content in stamens, gynoecia and glumes. The growing stage of B. glumae in spikelets could be divided into two sections. The biomass of all parts continued to increase to nearly 108 CFU/g at 10 DAI. This caused wilt symptoms and stopped the pollination. This work showed that glume hairs played an important role in the initial colonization of B. glumae, and provides a foundation for further studies of the infection manner of B. glumae and other pathogenic bacteria.