Infection Process of Burkholderia glumae in Rice Spikelets

Abstract

Burkholderia 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.

Seed-born Burkholderia glumae Infects Rice Seedling and Maintains Bacterial Population during Vegetative and Reproductive Growth Stage

“…Therefore, there are mainly two hypotheses of the entry of this pathogen to the plant. The first involves bacterial penetration through natural openings and/or wounds on roots, leaves and/or spikelet from an environmental reservoir of the bacteria ( Hikichi, 1993 ; Li et al, 2017 ; Tsushima et al, 1996 ). Direct spraying of B. glumae on plant leaves and spikelets has provided support for this mechanism of entry ( Tsushima et al, 1996 ).…”

“…Direct spraying of B. glumae on plant leaves and spikelets has provided support for this mechanism of entry ( Tsushima et al, 1996 ). More recently, Li and colleagues, sprayed directly a bacterial suspension of the B. glumae LMG 2196 strain, expressing the green fluorescent protein ( gfp ) gene, on leaves of plants at tillering stage using 10 ml at 1 × 10 9 cfu.ml −1 ( Li et al, 2016 ) and on spikelets using 1 ml at 7 × 10 8 cfu.ml −1 ( Li et al, 2017 ). These authors successfully showed B. glumae rice plant colonization of the vascular bundle through stomas, epidermal and leaf hairs infection ( Li et al, 2016 ), and colonization of gynoecium and stamens, after bacterial cell proliferation on glumae and penetration through glumae hairs ( Li et al, 2017 ).…”

“…More recently, Li and colleagues, sprayed directly a bacterial suspension of the B. glumae LMG 2196 strain, expressing the green fluorescent protein ( gfp ) gene, on leaves of plants at tillering stage using 10 ml at 1 × 10 9 cfu.ml −1 ( Li et al, 2016 ) and on spikelets using 1 ml at 7 × 10 8 cfu.ml −1 ( Li et al, 2017 ). These authors successfully showed B. glumae rice plant colonization of the vascular bundle through stomas, epidermal and leaf hairs infection ( Li et al, 2016 ), and colonization of gynoecium and stamens, after bacterial cell proliferation on glumae and penetration through glumae hairs ( Li et al, 2017 ). Similarly, to imitate the transmission of soil-borne of B. glumae , rice seeds have been inoculated using a bacterial suspension of the Pg-4 strain of Pseudomonas glumae ( B. glumae ) at 10 8 for 4 h ( Hikichi, 1993 ).…”

Advances in the Characterization of the Mechanism Underlying Bacterial Canker Development and Tomato Plant Resistance

“…There are no reports describing the invasion process of the Cm through the outer epidermis openings to specific locations within the epidermis in tomato hosts. An analysis of Burkholderia glumae, which is another bacterial species that infects plant vascular tissues, revealed that epidermal hairs and leaf hairs are the initial colonization sites [19]. Researchers examining the interior of maize leaves infected with another Clavibacter species observed that, after passing through the outer epidermis, C. nebraskensis colonizes leaves through epidermal junctions, cuticle depressions, stomata and the surrounding area, and the trichome base [20].…”

The Effect of Volume and Inoculation Method on the Development of Bacterial Panicle Blight Disease in Rice Plant

“…Based on studies was conducted by Li et al (2016) with the gfp gene marker, initially, B. glumae was in rice plants before panicle formation. Pathogenic bacteria initially surround the glume surface and colonize until the population increases in the glume hairs.…”