Department of Animal and Plant Biology, Center of Biological Sciences, State University of Londrina-UEL, Rodovia Celso Garcia Cid-PR445, km 380, Campus Universitário, Londrina, PR, 86057-970, Brazil.
Department of Agronomy, State University of Londrina, Londrina, PR, Brazil.
Planta. 2020 Mar 18;251(4):83. doi: 10.1007/s00425-020-03373-7.
Plant growth-promoting bacteria association improved the enzymatic and non-enzymatic antioxidant pathways in Neotropical trees under drought, which led to lower oxidative damage and enhanced drought tolerance in these trees. Water deficit is associated with oxidative stress in plant cells and may, thus, negatively affect the establishment of tree seedlings in reforestation areas. The association with plant growth-promoting bacteria (PGPB) is known to enhance the antioxidant response of crops, but this strategy has not been tested in seedlings of Neotropical trees. We evaluated the effects of inoculation with two PGPB (Azospirillum brasilense and Bacillus sp.) on the antioxidant metabolism of Cecropia pachystachya and Cariniana estrellensis seedlings submitted to drought. We measured the activity of antioxidant enzymes and the content of non-enzymatic antioxidants in leaves, and biometrical parameters of the seedlings. In both tree species, drought decreased the activity of antioxidant enzymes and the content of non-enzymatic antioxidant compounds. For C. pachystachya, the enzymatic and non-enzymatic pathways were mostly influenced by A. brasilense inoculation, which enhanced ascorbate peroxidase (APX) and superoxide dismutase activities and positively affected the level of non-enzymatic antioxidant compounds. In C. estrellensis, A. brasilense inoculation enhanced APX activity. However, A. brasilense and Bacillus sp. inoculation had more influence on the non-enzymatic pathway, as both bacteria induced a greater accumulation of secondary compounds (such as chlorogenic acid, gallic acid, rutin and synapic acid) compared to that in non-inoculated plants under drought. For both species, PGPB improved biometrical parameters related to drought tolerance, as specific leaf area and leaf-area ratio. Our results demonstrate that PGPB induced antioxidant mechanisms in drought-stressed Neotropical trees, increasing drought tolerance. Thus, PGPB inoculation provides a biotechnological alternative to improve the success of reforestation programmes.
植物促生菌联合作用提高了耐旱条件下新热带树木的酶和非酶抗氧化途径，从而降低了这些树木的氧化损伤并增强了其耐旱性。水分亏缺与植物细胞中的氧化应激有关，因此可能会对重新造林地区的树木幼苗的建立产生负面影响。已知与植物促生菌（PGPB）的联合作用可以增强作物的抗氧化反应，但这种策略尚未在新热带树木的幼苗中进行测试。我们评估了接种两种 PGPB（巴西固氮螺菌和芽孢杆菌）对 Cecropia pachystachya 和 Cariniana estrellensis 幼苗抗氧化代谢的影响，这些幼苗处于干旱胁迫下。我们测量了叶片中抗氧化酶的活性和非酶抗氧化剂的含量，以及幼苗的生物计量参数。在这两个树种中，干旱降低了抗氧化酶的活性和非酶抗氧化剂化合物的含量。对于 C. pachystachya，巴西固氮螺菌的接种主要影响了酶和非酶途径，增强了抗坏血酸过氧化物酶（APX）和超氧化物歧化酶的活性，并对非酶抗氧化剂化合物的水平产生了积极影响。在 C. estrellensis 中，巴西固氮螺菌的接种增强了 APX 活性。然而，巴西固氮螺菌和芽孢杆菌的接种对非酶途径的影响更大，因为与干旱条件下未接种植物相比，这两种细菌诱导了更多的次生化合物（如绿原酸、没食子酸、芦丁和莰菲醇）的积累。对于这两个树种，PGPB 改善了与耐旱性相关的生物计量参数，如比叶面积和叶面积比。我们的结果表明，PGPB 诱导了耐旱新热带树木的抗氧化机制，增强了其耐旱性。因此，PGPB 接种为提高重新造林计划的成功率提供了一种生物技术替代方案。
