Abstract
Plant-associated Stenotrophomonas isolates have great potential for plant growth promotion, especially under stress conditions, due to their ability to promote tolerance to abiotic stresses such as salinity or drought. The endophytic strain Stenotrophomonas sp. 169, isolated from a field-grown poplar, increased the growth of inoculated in vitro plants, with a particular effect on root development, and was able to stimulate the rooting of poplar cuttings in the greenhouse. The strain produced high amounts of the plant growth-stimulating hormone auxin under in vitro conditions. The comparison of the 16S rRNA gene sequences and the phylogenetic analysis of the core genomes showed a close relationship to Stenotrophomonas chelatiphaga and a clear separation from Stenotrophomonas maltophilia. Whole genome sequence analysis revealed functional genes potentially associated with attachment and plant colonization, growth promotion, and stress protection. In detail, an extensive set of genes for twitching motility, chemotaxis, flagella biosynthesis, and the ability to form biofilms, which are connected with host plant colonization, could be identified in the genome of strain 169. The production of indole-3-acetic acid and the presence of genes for auxin biosynthesis pathways and the spermidine pathway could explain the ability to promote plant growth. Furthermore, the genome contained genes encoding for features related to the production of different osmoprotective molecules and enzymes mediating the regulation of stress tolerance and the ability of bacteria to quickly adapt to changing environments. Overall, the results of physiological tests and genome analysis demonstrated the capability of endophytic strain 169 to promote plant growth. In contrast to related species, strain 169 can be considered non-pathogenic and suitable for biotechnology applications.
Highlights
Plant-associated microorganisms are gaining increasing recognition in terms of their importance for plant growth and health
The type species Stenotrophomonas maltophilia is a multidrug resistant ubiquitous opportunistic pathogen of environmental, mainly plant-associated, origin, and is commonly found in a wide range of environmental niches (Palleroni and Bradbury, 1993; Ryan et al, 2009; Berg and Martinez, 2015; Gopi et al, 2020). It has been described as a plant growth-promoting endophyte with beneficial effects due to its production of phytohormones and spermidine, phosphate solubilization, the potential to synthesize siderophores (Singh and Jha, 2017; Abdelaziz et al, 2018; Alexander et al, 2019; Wozniak et al, 2019; Aeron et al, 2020; Alijani et al, 2020) and its capability for bioprotection against fungal and bacterial pathogens (Narayanasamy, 2013; Kumar and Audipud, 2015; Elhalag et al, 2016; Rania et al, 2016)
It was possible to establish a new, clearly plant-associated species, Stenotrophomonas rhizophila (Wolf et al, 2002), that could be clearly differentiated from S. maltophilia and provides a harmless alternative for biocontrol without human health risks (Berg and Martinez, 2015; Pinski et al, 2020)
Summary
Plant-associated microorganisms are gaining increasing recognition in terms of their importance for plant growth and health. The type species Stenotrophomonas maltophilia is a multidrug resistant ubiquitous opportunistic pathogen of environmental, mainly plant-associated, origin, and is commonly found in a wide range of environmental niches (Palleroni and Bradbury, 1993; Ryan et al, 2009; Berg and Martinez, 2015; Gopi et al, 2020) It has been described as a plant growth-promoting endophyte with beneficial effects due to its production of phytohormones and spermidine, phosphate solubilization, the potential to synthesize siderophores (Singh and Jha, 2017; Abdelaziz et al, 2018; Alexander et al, 2019; Wozniak et al, 2019; Aeron et al, 2020; Alijani et al, 2020) and its capability for bioprotection against fungal and bacterial pathogens (Narayanasamy, 2013; Kumar and Audipud, 2015; Elhalag et al, 2016; Rania et al, 2016). The genome was investigated to reveal features explaining the beneficial effects for plant development and involved in stress tolerance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
