AUTHOR=Kang Xingxing , Guo Yu , Leng Shuang , Xiao Lei , Wang Lanhua , Xue Yarong , Liu Changhong 

TITLE=Comparative Transcriptome Profiling of Gaeumannomyces graminis var. tritici in Wheat Roots in the Absence and Presence of Biocontrol Bacillus velezensis CC09

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01474

DOI=10.3389/fmicb.2019.01474

ISSN=1664-302X

ABSTRACT=<p>This study aimed to explore potential biocontrol mechanisms involved in the interference of antagonistic bacteria with fungal pathogenicity <italic>in planta</italic>. To do this, we conducted a comparative transcriptomic analysis of the “take-all” pathogenic fungus <italic>Gaeumannomyces graminis</italic> var. <italic>tritici</italic> (<italic>Ggt</italic>) by examining <italic>Ggt</italic>-infected wheat roots in the presence or absence of the biocontrol agent <italic>Bacillus velezensis</italic> CC09 (<italic>Bv</italic>) compared with <italic>Ggt</italic> grown on potato dextrose agar (PDA) plates. A total of 4,134 differentially expressed genes (DEGs) were identified in <italic>Ggt</italic>-infected wheat roots, while 2,011 DEGs were detected in <italic>Bv</italic>+<italic>Ggt</italic>-infected roots, relative to the <italic>Ggt</italic> grown on PDA plates. Moreover, 31 DEGs were identified between wheat roots, respectively infected with <italic>Ggt</italic> and <italic>Bv</italic>+<italic>Ggt</italic>, consisting of 29 downregulated genes coding for potential <italic>Ggt</italic> pathogenicity factors – e.g., para-nitrobenzyl esterase, cutinase 1 and catalase-3, and two upregulated genes coding for tyrosinase and a hypothetical protein in the <italic>Bv</italic>+<italic>Ggt</italic>-infected roots when compared with the <italic>Ggt</italic>-infected roots. In particular, the expression of one gene, encoding the ABA3 involved in the production of <italic>Ggt</italic>’s hormone abscisic acid, was 4.11-fold lower in <italic>Ggt</italic>-infected roots with <italic>Bv</italic> than without <italic>Bv</italic>. This is the first experimental study to analyze the activity of <italic>Ggt</italic> transcriptomes in wheat roots exposed or not to a biocontrol bacterium. Our results therefore suggest the presence of <italic>Bv</italic> directly and/or indirectly impairs the pathogenicity of <italic>Ggt</italic> in wheat roots through complex regulatory mechanisms, such as hyphopodia formation, cell wall hydrolase, and expression of a papain inhibitor, among others, all which merit further investigation.</p>