Laboratory of Legumes, Center of Biotechnology of Borj Cedria, Hammam Lif, Tunisia.
National Agronomic Institute of Tunisia, University of Carthage, Tunis, Tunisia.
Plant Biol (Stuttg). 2018 Sep;20(5):857-869. doi: 10.1111/plb.12863. Epub 2018 Jul 19.
The ability of plant growth-promoting rhizobacteria (PGPR) to enhance Lathyrus sativus tolerance to lead (Pb) stress was investigated. Ten consortia formed by mixing four efficient and Pb-resistant PGPR strains were assessed for their beneficial effect in improving Pb (0.5 mM) uptake and in inducing the host defence system of L. sativus under hydroponic conditions based on various physiological and biochemical parameters. Lead stress significantly decreased shoot (SDW) and root (RDW) dry weight, but PGPR inoculation improved both dry weights, with highest increases in SDW and RDW of plants inoculated with I5 (R. leguminosarum (M5) + P. fluorescens (K23) + Luteibacter sp. + Variovorax sp.) and I9 (R. leguminosarum (M5) + Variovorax sp. + Luteibacter sp. + S. meliloti) by 151% and 94%, respectively. Additionally, inoculation significantly enhanced both chlorophyll and soluble sugar content, mainly in I5 inoculated leaves by 238% and 71%, respectively, despite the fact that Pb decreased these parameters. We also found that PGPR inoculation helps to reduce oxidative damage and enhances antioxidant enzyme activity, phenolic compound biosynthesis, carotenoids and proline content. PGPR inoculation increased Pb uptake in L. sativus, with highest increase in shoots of plants inoculated with I5 and I7, and in roots and nodules of plants inoculated with I1. Moreover, PGPR inoculation enhanced mineral homeostasis for Ca, Cu and Zn under Pb stress, mainly in plants inoculated with I1, I5, I7 and I9. Results of our study suggest the potential of efficient and Pb-resistant PGPR in alleviating harmful effects of metal stress via activation of various defence mechanisms and enhancing Pb uptake that promotes tolerance of L. sativus to Pb stress.
研究了植物促生根际细菌（PGPR）增强菜豆耐铅（Pb）胁迫的能力。基于各种生理生化参数，评估了由 4 种高效耐 Pb 根际细菌混合形成的 10 个共生体，以评估其在改善 Pb（0.5 mM）吸收和诱导 Lathyrus sativus 宿主防御系统方面的有益效果，实验在水培条件下进行。铅胁迫显著降低了地上部（SDW）和根部（RDW）干重，但 PGPR 接种提高了两者的干重，其中接种 I5（R. leguminosarum（M5）+P. fluorescens（K23）+Luteibacter sp.+Variovorax sp.）和 I9（R. leguminosarum（M5）+Variovorax sp.+Luteibacter sp.+S. meliloti）的植株地上部和根部干重的增加幅度最大，分别为 151%和 94%。此外，接种显著提高了叶绿素和可溶性糖的含量，主要是接种 I5 的叶片，分别增加了 238%和 71%，尽管铅降低了这些参数。我们还发现，PGPR 接种有助于减轻氧化损伤并增强抗氧化酶活性、酚类化合物生物合成、类胡萝卜素和脯氨酸含量。PGPR 接种增加了 L. sativus 对 Pb 的吸收，接种 I5 和 I7 的植株地上部和接种 I1 的植株根和根瘤中 Pb 的吸收增加幅度最大。此外，PGPR 接种增强了 Pb 胁迫下 Ca、Cu 和 Zn 的矿质元素稳态，主要是在接种 I1、I5、I7 和 I9 的植株中。我们的研究结果表明，高效耐 Pb 根际细菌通过激活各种防御机制和增强 Pb 吸收来缓解金属胁迫的有害影响，从而提高 L. sativus 对 Pb 胁迫的耐受性。
