El-Ballat Enas M, Elsilk Sobhy E, Ali Hayssam M, Ali Hamada E, Hano Christophe, El-Esawi Mohamed A
Botany Department, Faculty of Science, Tanta University, Tanta 31527, Egypt.
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.
Plants (Basel). 2023 May 26;12(11):2110. doi: 10.3390/plants12112110.
Heavy metal stress, including from chromium, has detrimental effects on crop growth and yields worldwide. Plant growth-promoting rhizobacteria (PGPR) have demonstrated great efficiency in mitigating these adverse effects. The present study investigated the potential of the PGPR strain EMCC1454 as a useful bio-inoculant for boosting the growth, performance and chromium stress tolerance of chickpea ( L.) plants exposed to varying levels of chromium stress (0, 130 and 260 µM KCrO). The results revealed that EMCC1454 could tolerate chromium stress up to 260 µM and exhibited various plant growth-promoting (PGP) activities, including nitrogen fixation, phosphate solubilization, and generation of siderophore, trehalose, exopolysaccharide, ACC deaminase, indole acetic acid, and hydrolytic enzymes. Chromium stress doses induced the formation of PGP substances and antioxidants in EMCC1454. In addition, plant growth experiments showed that chromium stress significantly inhibited the growth, minerals acquisition, leaf relative water content, biosynthesis of photosynthetic pigments, gas exchange traits, and levels of phenolics and flavonoids of chickpea plants. Contrarily, it increased the concentrations of proline, glycine betaine, soluble sugars, proteins, oxidative stress markers, and enzymatic (CAT, APX, SOD, and POD) and non-enzymatic (ascorbic acid and glutathione) antioxidants in plants. On the other hand, EMCC1454 application alleviated oxidative stress markers and significantly boosted the growth traits, gas exchange characteristics, nutrient acquisition, osmolyte formation, and enzymatic and non-enzymatic antioxidants in chromium-stressed plants. Moreover, this bacterial inoculation upregulated the expression of genes related to stress tolerance (, , , , , and ). Overall, the current study demonstrated the effectiveness of EMCC1454 in enhancing plant growth and mitigating chromium toxicity impacts on chickpea plants grown under chromium stress circumstances by modulating the antioxidant machinery, photosynthesis, osmolyte production, and stress-related gene expression.
包括铬在内的重金属胁迫对全球作物的生长和产量都有不利影响。植物促生根际细菌（PGPR）已证明在减轻这些不利影响方面具有很高的效率。本研究调查了PGPR菌株EMCC1454作为一种有用的生物接种剂的潜力，以促进暴露于不同水平铬胁迫（0、130和260μM K₂CrO₄）下的鹰嘴豆（Cicer arietinum L.）植株的生长、性能和铬胁迫耐受性。结果表明，EMCC1454能够耐受高达260μM的铬胁迫，并表现出多种植物促生（PGP）活性，包括固氮、解磷以及铁载体、海藻糖、胞外多糖、ACC脱氨酶、吲哚乙酸和水解酶的产生。铬胁迫剂量诱导了EMCC1454中PGP物质和抗氧化剂的形成。此外，植物生长实验表明，铬胁迫显著抑制了鹰嘴豆植株的生长、矿物质吸收、叶片相对含水量、光合色素的生物合成、气体交换特性以及酚类和黄酮类化合物的含量。相反，它增加了植物中脯氨酸、甘氨酸甜菜碱、可溶性糖、蛋白质、氧化应激标记物以及酶促（CAT、APX、SOD和POD）和非酶促（抗坏血酸和谷胱甘肽）抗氧化剂的浓度。另一方面，施用EMCC1454减轻了氧化应激标记物，并显著促进了铬胁迫植株的生长性状、气体交换特性、养分吸收以及渗透调节物质的形成和酶促及非酶促抗氧化剂的含量。此外，这种细菌接种上调了与胁迫耐受性相关基因（、、、、、和）的表达。总体而言，当前研究证明了EMCC1454通过调节抗氧化机制、光合作用、渗透调节物质的产生以及与胁迫相关的基因表达，在增强植物生长和减轻铬胁迫环境下生长的鹰嘴豆植株的铬毒性影响方面的有效性。
