Modulation of salt tolerance in Thai jasmine rice (Oryza sativa L. cv. KDML105) by Streptomyces venezuelae ATCC 10712 expressing ACC deaminase

Abstract

1-Aminocyclopropane-1-carboxylate (ACC) deaminase is a plant growth promoting (PGP) trait found in beneficial bacteria including streptomycetes and responsible for stress modulation. The ACC deaminase gene, acdS, of S. venezuelae ATCC 10712 was cloned into an expression plasmid, pIJ86, to generate S. venezuelae/pIJ86-acdS. Expression of acdS and production of ACC deaminase of S. venezuelae/pIJ86-acdS were significantly higher than the unmodified strain. The ACC deaminase-overexpressing mutant and the wild type control were inoculated into Thai jasmine rice (Oryza sativa L. cv. KDML105) under salt stress conditions. S. venezuelae on its own augmented rice growth and significantly increased more tolerance to salinity by reduction of ethylene, reactive oxygen species (ROS) and Na+ contents, while accumulating more proline, total chlorophyll, relative water content (RWC), malondialdehyde (MDA), and K+ than those of uninoculated controls. The overproducer did not alter chlorophyll, RWC, or MDA further–while it did boost more shoot weight and elongation, and significantly regulated salt tolerance of rice by increasing proline and reducing ethylene and Na+ contents further than that of the wild type. This work is the first illustration of the beneficial roles of S. venezuelae to enhance plant fitness endophytically by promotion of growth and salt tolerance of rice.

Halotolerant PGPR Stenotrophomonas maltophilia BJ01 Induces Salt Tolerance by Modulating Physiology and Biochemical Activities of Arachis hypogaea

“…The chlorophyll a, chlorophyll b and total chlorophyll contents were 0.4 mg g –1 Fw, 0.3 mg g –1 Fw, and 0.7 mg g –1 Fw respectively in a plant grown under salt stress with bacteria ( Figures 3A–C ). The positive effect of rhizospheric bacteria on chlorophyll content and photosynthetic ability of host plant under saline stress condition was also reported in Zea mays and Oryza sativa ( Nadeem et al, 2007 ; Rojas-Tapias et al, 2012 ; Yoolong et al, 2019 ). The protection of the photosynthetic pigment under salt stress was also reported in common bean ( Phaseolus vulgaris ) by rhizospheric bacteria ( Abdelmoteleb and Gonzalez-Mendoza, 2020 ).…”

The role of root‐associated microbes in growth stimulation of plants under saline conditions

“…and water, thereby increasing the biomass of plants in saline soil (Jaemsaeng et al, 2018;Yoolong et al, 2019); a similar growthpromoting effect was also obtained on tomato, due to the colonization of ACC-deaminase-producing Streptomyces. sp.…”

Understanding the potential of root microbiome influencing salt‐tolerance in plants and mechanisms involved at the transcriptional and translational level

“…KLBMP5084 showed enhanced growth promotion and disease resistance under saline conditions through the secretion of VOCs that helped in regulating ion homeostasis, antioxidative enzymes, and osmolytes in tomato plants (Gong et al, 2020). Qin et al, 2017;Yoolong et al, 2019; Table 1). Apart from the actinomycetes, secretion of exopolysaccharides by the endophytic strain-Pantoea alhagi NX-11 played a crucial role in overcoming salt stress damage in rice through the upregulation of proline synthase genes as well as by the increase in antioxidative enzyme activities (Sun et al, 2020)…”