Carreiras João, Caçador Isabel, Duarte Bernardo
MARE-Marine and Environmental Sciences Centre, ARNET-Aquatic Research Infrastructure Network Associated Laboratory, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal.
Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
Plants (Basel). 2022 Apr 13;11(8):1055. doi: 10.3390/plants11081055.
Plant growth-promoting rhizobacteria (PGPR) can promote plant growth through mechanisms such as mineral phosphates solubilization, biological N fixation and siderophores and phytohormones production. The present work aims to evaluate the physiological fitness improvement by PGPR in under mild and severe salt stress. PGPR-inoculated plants showed improved energy use efficiencies, namely in terms of the trapped and electron transport energy fluxes, and reduced energy dissipation. Allied to this, under mild stress, inoculated plants exhibited a significant reduction of the Na and Cl root concentrations, accompanied by a significant increase in K and Ca leaf content. This ion profile reshaping was intrinsically connected with an increased leaf proline content in inoculated plants. Moreover, bioaugmented plants showed an increased photoprotection ability, through lutein and zeaxanthin leaf concentration increase, allowing plants to cope with potentially photoinhibition conditions. Reduced Na leaf uptake in inoculated plants, apparently reduced the oxidative stress degree as observed by the superoxide dismutase and peroxidase activity reduction. Additionally, a reduced lipid peroxidation degree was observed in inoculated plants, while compared to their non-inoculated counterparts. These results, point out an important role of bioaugmentation in promoting plant fitness and improving salt tolerance, with a great potential for applications in biosaline agriculture and salinized soil restoration.
植物促生根际细菌（PGPR）可通过溶解矿物磷酸盐、生物固氮以及产生铁载体和植物激素等机制促进植物生长。本研究旨在评估PGPR在轻度和重度盐胁迫下对植物生理适应性的改善作用。接种PGPR的植物表现出能量利用效率提高，即在捕获和电子传递能量通量方面，且能量耗散减少。与此相关的是，在轻度胁迫下，接种植物的根中钠和氯浓度显著降低，同时叶片中钾和钙含量显著增加。这种离子分布的重塑与接种植物叶片脯氨酸含量增加内在相关。此外，通过增加叶片中叶黄素和玉米黄质的浓度，生物强化植物表现出增强的光保护能力，使植物能够应对潜在的光抑制条件。接种植物叶片对钠的吸收减少，这显然降低了超氧化物歧化酶和过氧化物酶活性所观察到的氧化应激程度。此外，与未接种的对照植物相比，接种植物的脂质过氧化程度降低。这些结果表明生物强化在促进植物适应性和提高耐盐性方面具有重要作用，在生物盐碱农业和盐碱化土壤修复中具有巨大的应用潜力。
