Stress-Tolerant Endophytic Isolate Priestia aryabhattai BPR-9 Modulates Physio-Biochemical Mechanisms in Wheat (Triticum aestivum L.) for Enhanced Salt Tolerance

Abstract

In efforts to improve plant productivity and enhance defense mechanisms against biotic and abiotic stresses, endophytic bacteria have been used as an alternative to chemical fertilizers and pesticides. In the current study, 25 endophytic microbes recovered from plant organs of Triticum aestivum L. (wheat) were assessed for biotic (phyto-fungal pathogens) and abiotic (salinity, drought, and heavy metal) stress tolerance. Among the recovered isolates, BPR-9 tolerated maximum salinity (18% NaCl), drought (15% PEG-6000), and heavy metals (µg mL−1): Cd (1200), Cr (1000), Cu (1000), Pb (800), and Hg (30). Based on phenotypic and biochemical characteristics, as well as 16S rDNA gene sequencing, endophytic isolate BPR-9 was recognized as Priestia aryabhattai (accession no. OM743254.1). This isolate was revealed as a powerful multi-stress-tolerant crop growth promoter after extensive in-vitro testing for plant growth-promoting attributes, nutrient (phosphate, P; potassium, K; and zinc, Zn) solubilization efficiency, extracellular enzyme (protease, cellulase, amylase, lipase, and pectinase) synthesis, and potential for antagonistic activity against important fungal pathogens viz. Alternaria solani, Rhizoctonia solani, Fusarium oxysporum, and Ustilaginoidea virens. At elevated salt levels, increases were noted in indole-3-acetic acid; siderophores; P, K, and Zn-solubilization; ACC deaminase; and ammonia synthesized by Priestia aryabhattai. Additionally, under in-vitro plant bioassays, wheat seedlings inoculated with P. aryabhattai experienced superior growth compared to non-inoculated seedlings in high salinity (0–15% NaCl) environment. Under NaCl stress, germination rate, plant length, vigor indices, and leaf pigments of wheat seedlings significantly increased following P. aryabhattai inoculation. Furthermore, at 2%-NaCl, B. aryabhattai greatly and significantly (p ≤ 0.05) decreased relative leaf water content, membrane damage, and electrolyte leakage compared with the non-inoculated control. Catalase, superoxide dismutase, and peroxidase activity increased by 29, 32, and 21%, respectively, in wheat seedlings exposed to 2% NaCl and inoculated with the bacteria. The present findings demonstrate that endophytic P. aryabhattai strains might be used in the future as a multi-stress reducer and crop growth promoter in agronomically important crops including cereals.

Metal-tolerant and siderophore producing Pseudomonas fluorescence and Trichoderma spp. improved the growth, biochemical features and yield attributes of chickpea by lowering Cd uptake

“…For qualitative estimation of siderophore, FeCl 3 test was performed by growing the microbial cultures in nutrient broth (NB) added with 0–400 µgCdmL −1 26 . Additionally, the production of siderophores were assessed using the previously described method 27 , which involved spot-inoculating of freshly grown cultures of strain PGPR-7 and T-4 onto chrome azurol S (CAS) agar plates that had been amended with different concentrations of Cd. The plates were examined for the development of a yellow to orange zone (halo), which indicates the release of siderophores, around bacterial growth after incubation.…”

Physio-Biochemical Responses of Three Aquilegia Species Seedlings to Salt Stress

“…Electrolyte leakage (EL) was measured by the conductivity method [24]. 0.2 g clean, fresh leaves tissue was immersed in 20 mL distilled water; then, after 8 min vacuuming, they were left to stand for 20 min before measuring the electrical conductivity.…”

“…The superoxide dismutase (SOD) activity (U/g) was measured with the nitroblue tetrazolium (NBT) method [24]. To obtain the enzyme solution, 0.5 g of fresh leaves tissue was ground with 5 mL 0.05 mol•L −1 phosphate buffer solution (pH = 7.8).…”

Synergistic relationship of endophyte-nanomaterials to alleviate abiotic stress in plants

“…These microbes are embedded in plants intercellularly, producing a symbiotic link (Roy et al, 2022). The advantage confers on the plant by the endophytes is to improve health status via various mechanisms, like the release of antimicrobial (antibacterial and antifungal) compounds and the secretion of growth-promoting metabolites (Shahid et al, 2022).…”