Cooperative interactions between seed-borne bacterial and air-borne fungal pathogens on rice

Boknam Jung,Won Cheol Kim,Suhkman Kim,Soyeon Kim,Jinnyun Kim,Yoonhee Kang,Kwang-Sik Lee ,Jong Cheol Shon,Kwang-Hyeon Liu,In-Young Kim ,Dahye Yoon,Taiying Li,Kihoon Yun,Bo Yeon Kim,Younghae Choi,Young Bong Seo ,Laura E Bartley,Namgyu Kim,Jung–Wook Park ,Hyun Hee Lee ,Sungyeon Ji,Jungkwan Lee

doi:10.1038/s41467-017-02430-2

Abstract

Bacterial-fungal interactions are widely found in distinct environments and contribute to ecosystem processes. Previous studies of these interactions have mostly been performed in soil, and only limited studies of aerial plant tissues have been conducted. Here we show that a seed-borne plant pathogenic bacterium, Burkholderia glumae (Bg), and an air-borne plant pathogenic fungus, Fusarium graminearum (Fg), interact to promote bacterial survival, bacterial and fungal dispersal, and disease progression on rice plants, despite the production of antifungal toxoflavin by Bg. We perform assays of toxoflavin sensitivity, RNA-seq analyses, lipid staining and measures of triacylglyceride content to show that triacylglycerides containing linolenic acid mediate resistance to reactive oxygen species that are generated in response to toxoflavin in Fg. As a result, Bg is able to physically attach to Fg to achieve rapid and expansive dispersal to enhance disease severity.

Highlights

Bacterial-fungal interactions are widely found in distinct environments and contribute to ecosystem processes
Burkholderia glumae (Bg) is often isolated with Fusarium graminearum (Fg) from field-grown rice grains
Rice grains were collected from black- and glutinous-type rice crops at intervals of 7 days (d) from the flowering times. Both Fg and Bg were frequently observed on the collected grains (Fig. 1a) and their coexistence frequencies were quantitated with a PCR-based assay that identified Fg and Bg as 420 bp and 138 bp products, respectively, (Fig. 1b)

Summary

Introduction

Bacterial-fungal interactions are widely found in distinct environments and contribute to ecosystem processes Previous studies of these interactions have mostly been performed in soil, and only limited studies of aerial plant tissues have been conducted. Bacterial-fungal interactions (BFI) widely exist in distinct environments, such as on the human body, in food and in soil[1,2,3,4] These interactions often have a physical or molecular basis[2,5], and they can lead to numerous biological effects that vary from antagonism to cooperation[2,6,7,8]. The data obtained demonstrate that the two pathogens cooperatively interact, and this provides Fg with an opportunity to produce more spores and toxins and it provides Bg with an opportunity to achieve aerial dispersal

Methods

Results

Conclusion