PGPR‐mediated expression of salt tolerance gene in soybean through volatiles under sodium nitroprusside

Abstract

Increasing evidence shows that nitric oxide (NO), a typical signaling molecule plays important role in development of plant and in bacteria-plant interaction. In the present study, we tested the effect of sodium nitroprusside (SNP)-a nitric oxide donor, on bacterial metabolism and its role in establishment of PGPR-plant interaction under salinity condition. In the present study, we adopted methods namely, biofilm formation assay, GC-MS analysis of bacterial volatiles, chemotaxis assay of root exudates (REs), measurement of electrolyte leakage and lipid peroxidation, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for gene expression. GC-MS analysis revealed that three new volatile organic compounds (VOCs) were expressed after treatment with SNP. Two VOCs namely, 4-nitroguaiacol and quinoline were found to promote soybean seed germination under 100 mM NaCl stress. Chemotaxis assay revealed that SNP treatment, altered root exudates profiling (SS-RE), found more attracted to Pseudomonas simiae bacterial cells as compared to non-treated root exudates (S-RE) under salt stress. Expression of Peroxidase (POX), catalase (CAT), vegetative storage protein (VSP), and nitrite reductase (NR) genes were up-regulated in T6 treatment seedlings, whereas, high affinity K transporter (HKT1), lipoxygenase (LOX), polyphenol oxidase (PPO), and pyrroline-5-carboxylate synthase (P5CS) genes were down-regulated under salt stress. The findings suggest that NO improves the efficiency and establishment of PGPR strain in the plant environment during salt condition. This strategy may be applied on soybean plants to increase their growth during salinity stress.

Do volatile compounds produced by Fusarium oxysporum and Verticillium dahliae affect stress tolerance in plants?

“…In addition, VC-treated plants had increased leaf chlorophyll content (Figure 1(c)) and lateral root density (Figure 1(d)). Similarly, VCs produced by certain PGPR strains also improved plant growth under salt stress (Zhang et al 2008, 2010; Vaishnav et al 2015, 2016; Ledger et al 2016). Decreased leaf surface area and chlorophyll content are common plant responses to salt stress, resulting in reduced photosynthesis and growth (Netondo et al 2004; Hasanuzzaman et al 2013; Negrão et al 2017).…”

“…Trichoderma virens and Trichoderma atroviride helped the growth of Arabidopsis thaliana under high NaCl conditions by restoring auxin homeostasis (Contreras-Cornejo et al 2014). Volatile compounds (VCs) produced by some plant growth promoting rhizobacteria (PGPR) have been shown to alleviate plant salt stress (Zhang et al 2008, 2010; Vaishnav et al 2015, 2016; Ledger et al 2016). VCs produced by Bacillus amyloliquefaciens GB03 conferred increased salt tolerance in A. thaliana presumably via tissue-specific regulation of HKT1 , a high-affinity K + transporter, and induced accumulation of osmoprotectants (Zhang et al 2008, 2010).…”

“…4-nitroguaiacol and quinoline) or a mix of VCs (e.g. 2-undecanone, 7-hexanol and 3-methylbutanol) also caused better growth under salt stress (Ledger et al 2016; Vaishnav et al 2016). …”

Hydrogen sulfide: a new endogenous player in an old mechanism of plant tolerance to high salinity

“…Avicennia marina (Chen et al 2010) Cucumis sativus (Shi et al 2007) Cynodon dactylon (Liu et al 2016) Gossypium hirsutum (Liu et al 2013;Kong et al 2016) Kandelia obovata (Lang et al 2014) Aegiceras corniculatum (Lang et al 2014) Limonium bicolor (Ding et al 2013) Populus euphratica Triticum aestivum (Tian et al 2015) Induction of osmoregulators accumulation Brassica juncea (Zeng et al 2011;Khan et al 2012) Cicer arietinum (Ahmad et al 2016) Cucumis sativus (Fan et al 2013) Gossypium hirsutum (Liu et al 2013) Lycopersicom esculentum ) Solanum lycopersicum (Hayat et al 2012) Triticum aestivum (Tian et al 2015) Induction of polyamines accumulation Cucumis sativus (Fan et al 2013) Protection of photosynthetic apparatus Brassica juncea (Fatma et al 2016) Cicer arietinum (Ahmad et al 2016) Fragaria × ananassa (Christou et al 2014) Gossypium hirsutum (Kong et al 2016) Medicago truncatula (Jian et al 2016) Stimulation of seed germination Arabidopisis thaliana (Zhao et al 2007) Triticum aestivum (Zheng et al 2008) Zea mays (Bai et al 2011) Stimulation of plant growth Arabidopisis thaliana ) Glycine max (Egbichi et al 2014;Vaishnav et al 2016) Gossypium hirsutum and increased chlorophylls content and photosynthetic rate (Kong et al 2016). The NO and sulfur nutrition were found to prevent chloroplasts damage in salt-exposed mustard (B. juncea) plants (Fatma et al 2016).…”

“…The application of an NO donor on NaCl-treated soybean improved plants growth and biomass accumulation in shoot, root and nodules (Egbichi et al 2014;Vaishnav et al 2016). Indeed, the NaCl-triggered disruption of Pseudomonas simiae (rhizobacteria) colonization in soybean was reverted by 100 µM SNP and allowed plant to tolerate salt stress (Vaishnav et al 2016).…”