AUTHOR=Webster Gordon , Mullins Alex J. , Petrova Yoana D. , Mahenthiralingam Eshwar 

TITLE=Polyyne-producing Burkholderia suppress Globisporangium ultimum damping-off disease of Pisum sativum (pea)

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1240206

DOI=10.3389/fmicb.2023.1240206

ISSN=1664-302X

ABSTRACT=<p>Extensive crop losses are caused by oomycete and fungal damping-off diseases. Agriculture relies heavily on chemical pesticides to control disease, but due to safety concerns multiple agents have been withdrawn. <italic>Burkholderia</italic> were successfully used as commercial biopesticides because of their fungicidal activity and plant protective traits. However, their potential for opportunistic pathogenicity led to a moratorium on their registration as biopesticides. Subsequently, <italic>Burkholderia</italic> were shown to produce multiple specialised metabolites including potent antimicrobial polyynes. Cepacin A, a polyyne produced by <italic>Burkholderia ambifaria</italic> biopesticide strains was shown to be an important metabolite for the protection of germinating peas against <italic>Globisporangium ultimum</italic> (formerly <italic>Pythium</italic>) damping-off disease. Recently, there has been an expansion in bacterial polyyne discovery, with the metabolites and their biosynthetic gene pathways found in several bacterial genera including <italic>Burkholderia</italic>, <italic>Collimonas</italic>, <italic>Trinickia</italic>, and <italic>Pseudomonas</italic>. To define the efficacy of these bacterial polyyne producers as biopesticidal agents, we systematically evaluated metabolite production, <italic>in vitro</italic> microbial antagonism, and <italic>G. ultimum</italic> biocontrol across a panel of 30 strains representing four bacterial genera. <italic>In vitro</italic> polyyne production and antimicrobial activity was demonstrated for most strains, but only <italic>Burkholderia</italic> polyyne producers were protective within the <italic>in vivo G. ultimum</italic> damping-off pea protection model. <italic>B. ambifaria</italic> was the most effective cepacin-expressing biopesticide, and despite their known potential for plant pathogenicity <italic>Burkholderia gladioli</italic> and <italic>Burkholderia plantarii</italic> were uniquely shown to be protective as caryoynencin-producing biopesticides. In summary, <italic>Burkholderia</italic> are effective biopesticides due to their suite of antimicrobials, but the ability to deploy polyyne metabolites, caryoynencin and cepacin, is strain and species dependent.</p><p><fig position="float" id="fig4"><label>Graphical Abstract</label><graphic xlink:href="fmicb-14-1240206-g004.tif" xmlns:xlink="http://www.w3.org/1999/xlink" /></fig></p>