解淀粉芽孢杆菌增强燕麦干旱适生性及促生基因分析

Bacillus amyloliquefaciens enhances the drought tolerance of oat plants by regulating the expression of plant growth-promoting genes

摘要:

目的 探究分离自青藏高原干旱沙地的解淀粉芽孢杆菌(Bacillus amyloliquefaciens) DGL1对干旱胁迫下燕麦(Avena sativa)的促生特性及机制，以期为适用于干旱地区的菌肥研发提供优质菌源和理论基础。方法 测定干旱胁迫下菌株DGL1对燕麦根长、株高、鲜重的促生效果，测定燕麦在干旱胁迫下的细胞膜过氧化程度及抗氧化酶活性，并利用高通量测序技术对菌株DGL1进行全基因组测序和转录组学测序。结果 研究发现DGL1显著增加了干旱胁迫下燕麦的根长、株高和鲜重，显著提高了燕麦抗氧化酶超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)、过氧化物酶(peroxidase, POD)的活性，降低了丙二醛和H₂O₂的含量。全基因组测序表明，DGL1具有谷胱甘肽过氧化物酶编码基因gpx、甘氨酸甜菜碱转运蛋白编码基因OpuD、烷基过氧化氢还原酶编码基因ahpF等与氧化应激相关的基因，还具有IAA前体l-色氨酸基因trpA、trpB、trpC等，以及鞭毛生物合成蛋白编码基因FliP、FliQ、FliR等。此外，通过转录组测序发现，干旱胁迫下与根定殖相关的生物膜形成、氮磷吸收利用及物质能量代谢、生长素前体合成等相关基因均上调表达，菌株可能通过这些途径增强了植物对干旱胁迫的耐受能力。结论 菌株DGL1能够增强燕麦对干旱的适生性，具有在旱地研发生物制剂的潜能。

Abstract:

Objective To investigate the growth-promoting properties and mechanisms of Bacillus amyloliquefaciens DGL1 isolated from arid sandy soils of the Qinghai-Xizang Plateau on oat plants under drought stress, thus providing a high-quality microbial resource and a theoretical basis for developing microbial fertilizers suitable for arid regions.Methods The growth-promoting effects of strain DGL1 on oat root length, plant height, and fresh weight under drought stress were determined. The degree of cell membrane lipid peroxidation and the activities of antioxidant enzymes in oat plants under drought stress were measured. The genome and transcriptome of strain DGL1 were sequenced via high-throughput technology.Results Strain DGL1 significantly increased the root length, plant height, and fresh weight of oat plants under drought stress. It markedly elevated the activities of antioxidant enzymes [(superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)] while reducing the content of malondialdehyde and H₂O₂. Genomic analysis revealed that DGL1 carried the genes related to oxidative stress (gpx encoding glutathione peroxidase, opuD encoding glycine-betaine transporter, and ahpF encoding alkyl hydroperoxide reductase), synthesis of the IAA precursor l-tryptophan (trpA, trpB, and trpC), and flagellar biosynthesis (FliP, FliQ, and FliR). Transcriptome sequencing further revealed that genes associated with biofilm formation, nitrogen and phosphorus uptake, material and energy metabolism, and auxin precursor synthesis—all crucial for root colonization—presented upregulated expression under drought stress. The strain might enhance plant drought tolerance via these pathways.Conclusion Strain DGL1 can enhance the drought tolerance of oat plants and has great potential for application in developing bio-inoculants for arid land agriculture.