Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau 275103, India.
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India.
Int J Environ Res Public Health. 2022 Sep 1;19(17):10883. doi: 10.3390/ijerph191710883.
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 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): 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 (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. , , , and . At elevated salt levels, increases were noted in indole-3-acetic acid; siderophores; P, K, and Zn-solubilization; ACC deaminase; and ammonia synthesized by . Additionally, under in-vitro plant bioassays, wheat seedlings inoculated with 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 inoculation. Furthermore, at 2%-NaCl, greatly and significantly ( ≤ 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 strains might be used in the future as a multi-stress reducer and crop growth promoter in agronomically important crops including cereals.
为了提高植物生产力和增强对生物和非生物胁迫的防御机制，内共生细菌已被用作化学肥料和农药的替代品。在本研究中，从 L.（小麦）植物器官中回收了 25 种内生微生物，以评估其对生物（植物真菌病原体）和非生物（盐度、干旱和重金属）胁迫的耐受性。在回收的分离物中，BPR-9 耐受最大盐度（18%NaCl）、干旱（15%PEG-6000）和重金属（µg mL）：Cd（1200）、Cr（1000）、Cu（1000）、Pb（800）和 Hg（30）。基于表型和生化特征以及 16S rDNA 基因测序，内共生分离物 BPR-9 被鉴定为 （登录号 OM743254.1）。在进行了广泛的体外植物生长促进特性、养分（磷酸盐、P；钾、K；和锌、Zn）溶解效率、胞外酶（蛋白酶、纤维素酶、淀粉酶、脂肪酶和果胶酶）合成以及对重要真菌病原体的拮抗活性测试后，该分离物被证明是一种强大的多胁迫耐受作物生长促进剂，这些真菌病原体包括 、 、 和 。在高盐水平下，吲哚-3-乙酸；铁载体；P、K 和 Zn 溶解；ACC 脱氨酶；和由 合成的氨增加。此外，在体外植物生物测定中，与未接种的幼苗相比，接种 的小麦幼苗在高盐（0-15%NaCl）环境中表现出更好的生长。在 NaCl 胁迫下，接种 后，小麦幼苗的发芽率、株高、活力指数和叶片色素显著增加。此外，在 2%-NaCl 下，与未接种的对照相比， 大大且显著（ ≤ 0.05）降低了相对叶片水分含量、膜损伤和电解质泄漏。暴露于 2%NaCl 并接种细菌的小麦幼苗中的过氧化氢酶、超氧化物歧化酶和过氧化物酶活性分别增加了 29%、32%和 21%。本研究结果表明，内生 菌株未来可能被用作农业上重要作物（包括谷类作物）的多胁迫缓解剂和作物生长促进剂。
