Brevibacterium linens RS16 confers salt tolerance to Oryza sativa genotypes by regulating antioxidant defense and H+ ATPase activity

Abstract

Soil salinity is one of the major limitations that affects both plant and its soil environment, leading to reduced agricultural production. Evaluation of stress severity by plant physical and biochemical characteristics is an established way to study plant-salt stress interaction, but the halotolerant properties of plant growth promoting bacteria (PGPB) along with plant growth promotion is less studied till date. The aim of the present study was to elucidate the strategy, used by ACC deaminase-containing halotolerant Brevibacterium linens RS16 to confer salt stress tolerance in moderately salt-tolerant (FL478) and salt-sensitive (IR29) rice (Oryza sativa L.) cultivars. The plants were exposed to salt stress using 0, 50, and 100 mM of NaCl with and without bacteria. Plant physiological and biochemical characteristics were estimated after 1, 5, 10 days of stress application. H ATPase activity and the presence of hydroxyectoine gene (ectD) that is responsible for compatible solute accumulation were also analyzed in bacteria. The height and dry mass of bacteria inoculated plants significantly increased compared to salt-stressed plants, and the differences increased in time dependent manner. Bacteria priming reduced the plant antioxidant enzyme activity, lipid peroxidation and it also regulated the salt accumulation by modulating vacuolar H ATPase activity. ATPase activity and presence of hydroxyectoine gene in RS16 might have played a vital role in providing salt tolerance in bacteria inoculated rice cultivars. We conclude that dual benefits provided by the halotolerant plant growth promoting bacteria (PGPB) can provide a major way to improve rice yields in saline soil.

Transcriptome Analysis of Ice Plant Growth-Promoting Endophytic Bacterium Halomonas sp. Strain MC1 to Identify the Genes Involved in Salt Tolerance

“…ATPase activity coupled with the transmembrane movement of substances (GO:0042626), active transmembrane transporter activity (GO:0022804), and primary active transmembrane transporter activity (GO:0015399) were significantly enriched in the molecular function category (Figure 4). A previous work showed that Brevibacterium confers salt tolerance by regulating the ATPase activity [40]. In accordance with this result, our data suggest that this activity aids bacteria in surviving under salt stress.…”

Inoculation of Brevibacterium linens RS16 in Oryza sativa genotypes enhanced salinity resistance: Impacts on photosynthetic traits and foliar volatile emissions

“…In particular, B. linens RS16 which has been used in the present study had been screened for nitrogen fixation, indole acetic acid production, thiosulfate production, exopolysaccharide production, protease, cellulase, lipase and ACC deaminase activity (Siddikee et al, 2010, 2011). The B. linens RS16 inoculation has shown to play a significant role in increasing rice plant root length, shoot length and dry weight even under 100 mM salt stress (Chatterjee et al, 2018). However, it was also observed that the foliar Na + / K + ratio has significant positive correlation with total volatile emission, ACC accumulation and ACO activity in both the rice cultivars (Fig.…”

“…In the present study, two rice cultivars IR29 (salt-sensitive) and FL478 (moderately salt resistant) were used, to analyze the quantitative responses of carbon assimilation and stress volatile emissions to the combined effects of salinity and inoculation by the halotolerant PGPB Brevibacterium linens RS16, which was isolated from coastal soils in South Korea in a study, that aimed at isolating PGPBs to tolerate salt stress (Siddikee et al, 2010). This isolate can grow even at very salty conditions, > 1.7 M NaCl, and has been shown to possess ACC deaminase activity and support plant growth under saline condition (Siddikee et al, 2011; Chatterjee et al, 2018).…”

Methylobacterium oryzae CBMB20 influences photosynthetic traits, volatile emission and ethylene metabolism in Oryza sativa genotypes grown in salt stress conditions

“…However, there is evidence that the constitutive level of salinity stress protection mechanisms and induction of these mechanisms under salinity is very limited in rice (Yeo et al 1999). Indeed, previous studies have even indicated that salinity could even reduce H + ATPase activity in rice (Chatterjee et al 2018). There are several approaches to alleviate salinity stress in plants such as including cation foliar application (Sultana et al 2001), selective breeding for salinity resistant lines, gene transformation for improving salinity resistance, and using plant growth promoting bacteria (PGPB) (Deinlein et al 2014; Gupta and Huang 2014).…”