An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes

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.

Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

“…Poplar (Populus) and willow (Salix) trees of the Salicaceae have a wide global distribution, both in native riparian forests across the Northern Hemisphere and in planted forests, accounting for more than 95 million hectares globally (fao.org). Native poplar trees have a diverse microbiota, many with the ability to fix dinitrogen gas, solubilize phosphate, and promote plant growth and health especially under abiotic stresses such as drought and nutrient limitation (Doty et al, 2005Xin et al, 2009;Khan et al, 2012Khan et al, , 2015Khan et al, , 2016Kandel et al, 2015Kandel et al, , 2017Doty, 2016;Aghai et al, 2019). Beneficial microbiota have been isolated from hybrid poplar trees grown in contaminated sites, in field sites, or in tissue culture (Moore et al, 2006;Ulrich et al, 2008;Barac et al, 2009;Scherling et al, 2009;Taghavi et al, 2009).…”

Plant responses underlying nonhost resistance of Citrus limon against Xanthomonas campestris pv. campestris

“…Based on these results, we propose that Xcc , acting as an endophyte inside the plant, has the potential to maintain activated the inducible defence responses. It has been observed that endophytic bacteria act by inducing priming and protecting plants against biotic and abiotic stress (Kandel et al ., ; Pavlo et al ., ). It has been reported that bacterial endophytes increase defence enzymes, such as PAL, and antioxidant activity, such as superoxide dismutase (SOD), and enhance callose deposition and SA‐responsive genes in host‐treated plants (Liu et al ., ; Mishra et al ., ).…”

Characterization, identification and antibiogram studies of endophytic bacteria from cowpea [Vigna unguiculata (L.) Walp]

“…Here all three isolates were showed antibiotic sensitivity against seven (7), and are harmless to environment for suitable application (Alström and Vuurde, 2001) and their antimicrobial activity could be exploited in biotechnology, medicine and agriculture (Gashgari et al, 2016) to control pathogen attack in cowpea and possibly in other plants. A number of endophytic bacteria were reported to prevent the deleterious effects of certain pathogens by producing antimicrobial compunds or inducing systemic resistance in the host plant (Kandel et al, 2017). Hence, discovery of novel and effective antibiotics are necessary (O'Donnell et al, 2010).…”