乌兰布和沙漠四翅滨藜根际、内生细菌的促生作用及其复合菌群的构建

Evaluation of plant growth-promoting effects of rhizosphere and endophytic bacteria of Atriplex canescens in the Ulan Buh Desert and construction of strain combinations

摘要:

四翅滨藜是荒漠抗逆先锋树种，也是肉苁蓉主要寄主，在内蒙古乌兰布和沙漠地区广泛种植。根际及内生微生物在植物生长发育和抗逆境过程中发挥重要作用。然而，关于内蒙古乌兰布和沙漠地区四翅滨藜根际与内生微生物的促生功能研究尚较为匮乏。目的 筛选内蒙古乌兰布和沙漠地区四翅滨藜根际及内生细菌中的促生菌株，为该地区四翅滨藜的可持续繁育提供微生物菌种资源。方法 从内蒙古磴口县乌兰布和沙漠采集四翅滨藜根际土和植株样品，分离纯化四翅滨藜根际和内生细菌，探究这些细菌与课题组前期得到的黄芪促生细菌对四翅滨藜幼苗的促生效果，对具有显著促生效果的菌株进行分子生物学鉴定和促生功能分析，然后对这些菌进行复配组合构建人工复合菌群，并检测复合菌群对四翅滨藜的促生效果。结果 共分离得到60株四翅滨藜根际细菌和14株内生细菌，其中2株内生细菌具有显著促生作用，检测的黄芪促生菌中有3株菌对四翅滨藜具有显著促生作用。5株促生细菌分属于3个属和4个种，包括假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)和不动杆菌属(Acinetobacter)。这些促生菌株均具有不同水平的固氮、解无机磷、解有机磷、解钾长石、解硅酸铝钾、产吲哚-3-乙酸(indole-3-acetic acid, IAA)和产生物膜的能力，大多数菌株具有产铁载体的能力。人工复合菌群中多个组合均具有促进效果，组合2 (IH-2、IH-9、TYA27)、3 (IH-2、IH-9、PAS13-2)和4 (IH-2、TYA39、TYA27)综合促生效果最好，毕节假单胞菌(Pseudomonas bijieensis) IH-2为核心菌株。结论 乌兰布和沙漠地区四翅滨藜的促生菌主要包括假单胞菌属(Pseudomonas)和芽孢杆菌属(Bacillus)，毕节假单胞菌(P. bijieensis)在促生复合菌群中起核心作用。

Abstract:

As a pioneer species in desert areas and the main host of Cistanche deserticola, Atriplex canescens is widely planted in the Ulan Buh Desert in Inner Mongolia. Rhizosphere and endophytic microorganisms play a significant role in the growth and stress resistance of plants. However, few studies have been conducted on the growth-promoting functions of rhizosphere and endophytic bacteria on A. canescens in the Ulan Buh Desert.Objective We screened plant growth-promoting strains from the rhizosphere and endophytic bacteria of A. canescens, aiming to provide microbial resources for the sustainable breeding of A. canescens in this region.Methods Rhizosphere soil and plant samples of A. canescens were collected from the Ulan Buh Desert in Dengkou County, Inner Mongolia. Rhizosphere and endophytic bacteria were isolated and purified. The plant growth-promoting effects of these bacteria and the plant growth-promoting bacteria of Astragalus previously obtained by our research group on A. canescens seedlings were investigated. Molecular biological identification and functional analysis were conducted on the strains with significant plant growth-promoting effects. Then, these strains were combined and the growth-promoting effects of the strain combinations on A. canescens were evaluated.Results A total of 60 rhizosphere bacterial strains and 14 endophytic bacterial strains of A. canescens were isolated. Two endophytic bacterial strains significantly promoted the growth of A. canescens seedlings. Among the Astragalus growth-promoting bacteria tested, three strains had significant growth-promoting effects on A. canescens seedlings. The five plant growth-promoting strains were identified as four species belonging to three genera: Pseudomonas, Bacillus, and Acinetobacter. These strains had different levels of nitrogen fixation, inorganic and organic phosphorus solubilization, potassium feldspar and potassium aluminum silicate solubilization, and indole-3-acetic acid (IAA) and biofilm production. Most of the strains had the ability to produce siderophores. Multiple strain combinations promoted the growth of A. canescens. Combinations 2 (IH-2, IH-9, and TYA27), 3 (IH-2, IH-9, and PAS13-2) and 4 (IH-2, TYA39, and TYA27) demonstrated the best comprehensive plant growth-promoting effects, with Pseudomonas bijieensis IH-2 as the core strain.Conclusion The growth-promoting bacteria of A. canescens in the Ulan Buh Desert mainly include Pseudomonas and Bacillus. P. bijieensis plays a core role in the plant growth-promoting bacterial combinations.