Rhizospheric pathogen proliferation and ROS production are associated with premature senescence of the osvha-a1 rice mutant

Abstract

Root-pathogen interactions influence premature senescence in rice, however, few studies have addressed the underlying mechanism. In this study, when premature senescence significantly occurred in the osvha-a1 mutant (loss of tonoplast H+-ATPase activity), the relative abundance of rhizospheric bacterial communities was similar between the mutant and its wild type, while the fungi in the rhizosphere of the osvha-a1 mutant significantly differed from the wild type. Furthermore, one key fungal strain in the rhizospheric soil of the osvha-a1 mutant, Gibberella intermedia, increased substantially during the late growing phase, resulting in severe accumulation of reactive oxygen species (ROS). By contrast, the wild type showed much lower levels of ROS when infected by G. intermedia. Using high performance liquid chromatography, sugars in root exudates were identified to be different between osvha-a1 mutant and the wild type. G. intermedia could use mannose and rhamnose in root exudates from the mutant more efficiently than any other sugar. Finally, antagonistic bacteria could be employed for limiting the proliferation of G. intermedia in the rhizosphere, thereby alleviating the early senescent phenotypes of the osvha-a1 mutant, and improving grain yield.

Keywords: Gibberella intermedia; OsVHA-A1; Antagonistic bacteria; HPLC; ROS accumulation; mannose and rhamnose; microbiota; premature senescence of rice.