Salinity alleviator bacteria in rice (Oryza sativa L.), their colonization efficacy, and synergism with melatonin

Abstract

In this study, rhizospheric and endophytic bacteria were tested for the alleviation of salinity stress in rice. Endophytic isolates were taken from previous studies based on their salt stress-alleviating traits. The rhizospheric bacteria were isolated from rice and screened based on salt tolerance and plant growth-promoting traits. Molecular identification indicated the presence of class Gammaproteobacteria, Bacillota, and Actinomycetia. Two-two most potential isolates each from rhizospheric and endophytic bacteria were selected for in planta trials. Results showed that microbial inoculation significantly improved germination and seedling vigor under elevated salinity. The confocal scanning laser microscopy showed higher bacterial colonization in inoculated rice roots than in control. Based on this experiment, rhizospheric bacteria Brevibacterium frigoritolerans W19 and endophytic Bacillus safensis BTL5 were selected for pot trial along with a growth-inducing compound melatonin 20 ppm. Inoculation of these two bacteria improved the levels of chlorophyll, proline, phenylalanine ammonia-lyase, catalase, superoxide dismutase, polyphenol oxidase, root-shoot length, and dry weight under elevated salt concentration. The gene expression studies showed modulation of SOD1, CATa, NHX1, and PAL1 genes by the bacterial strains and melatonin application. The inoculation was found to have additive effects with 20 ppm melatonin. This enhancement in dry matter accumulation, compatible solute production, and oxidative stress regulation could help plants in mitigating the ill effects of high salinity. Exploring such a combination of microbes and inducer molecules could be potentially useful in developing stress-alleviating bioformulations.

Microbial community assembly and functional profiles along the soil-root continuum of salt-tolerant Suaeda glauca and Suaeda salsa

“…The keystone species of bacteria were mainly assigned to Gammaproteobacteria and Alphaproteobacteria (Table S5), consistent with the results of community composition and community differences in ASV levels (Figures 3A, 5). As generally found, Gammaproteobacteria and Alphaproteobacteria communities in the endosphere tended to be phylogenetically assembled (Gupta et al, 2022), indicating that the aggregation of these groups near the roots might play important roles in plant saline-alkali tolerance. Faced with complex environments, plants might recruit specific microorganisms to alleviate stress.…”

Colonization potential of endophytes from halophytic plants growing in the “Runn of Kutch” salt marshes and their contribution to mitigating salt stress in tomato cultivation

“…Staining for H 2 O 2 and superoxide accumulation also supported these findings. Other reports also suggest that the microbes which are able to directly or indirectly reduce either of these effects could ameliorate salinity stress in plants ( Gupta et al, 2023a , b ).…”

“…The capacity of the chosen endophytes to tolerate NaCl was further assessed as per the protocol followed by Gupta et al (2023b) . The isolates were grown/cultured in NB media supplemented with various sodium chloride (NaCl) levels (0, 400, 800, 1,200, 1,600, and 2000 mM) for this, then incubated at 28 ± 2°C in a shaking incubator (at 150 rpm) for two to 3 days.…”