An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes
Author(s)
Date Issued
2017
Type
article
Volume
8
Journal
Abstract
Microbial communities in the endosphere of Salicaceae plants, poplar (Populus
trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for
plant growth promotion, protection from biotic and abiotic stresses, and degradation
of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae
endophytes against various soil borne plant pathogens including Rhizoctonia solani
AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum.
Additionally, different plant growth promoting traits such as biological nitrogen fixation
(BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore
production were assessed in all bio-control positive strains. Burkholderia, Rahnella,
Pseudomonas, and Curtobacterium were major endophyte genera that showed
bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia
strains were stronger across all tested plant pathogens as compared to other stains.
Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify
the putative genes involved in the bio-control activities. The ocf and hcnABC gene
clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and
hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte
strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate,
and synthesized siderophores in the culture medium. Moreover, some strains reduced
acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF.
Salicaceae endophytes could be useful for bio-control of various plant pathogens, and
plant growth promotion possibly through the mechanisms of BNF, IAA production, and
nutrient acquisition.
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