高寒草地产胞外多糖植物根际促生菌筛选及促生特性研究

Screening and studying the growth-promoting characteristics of exopolysaccharide-producing plant growth-promoting rhizobacteria in alpine grassland

摘要:

【目的】 筛选若尔盖高寒草地高产胞外多糖PGPR，为研制适宜若尔盖高寒草地的多糖菌剂及相关产品提供优良菌种资源。【方法】 在16 ℃条件下，利用选择性培养基从高寒草地的波伐早熟禾（Poa poophagorum）和老芒麦（Elymus sibiricus）根际筛选高产胞外多糖PGPR，利用16S rDNA 测序与系统发育分析明确分类地位，通过接种试验研究菌株和胞外多糖的促生特性。【结果】 从两种植物根际筛选到3 株产胞外多糖PGPR，其中，菌株NAHP4、PBRS1 高产胞外多糖，产糖量分别为1 462. 50、1 337. 50 mg/L，并兼具固氮、溶无机磷的促生特性；胞外多糖对老芒麦的种子萌发和胚芽生长具有促进作用，高浓度的胞外多糖对胚根生长具有显著抑制作用（P＜0. 05）；接种菌株NAHP4、NBHP13、PBRS1 对老芒麦地下部分具有显著促进作用（P＜0. 05），其中，菌株NAHP4 的促进作用最大。【结论】菌株NAHP4 作为高产胞外多糖PGPR 资源，具有研发适宜若尔盖高寒草地的多糖菌剂及相关产品的潜力。

Abstract:

【Objective】 To screen high exopolysaccharide ‐ producing PGPR resources from the Zoige alpinegrassland in order to provide valuable strains for developing Polysaccharide bacterial reagents suitable for Zoige alpinegrassland and related products.【Method】 At 16 ℃，high exopolysaccharide-producing PGPR was isolatedf rom therhizosphere of Poa poophagorum and Elymus sibiricus in alpine grassland using selective media. Their taxonomic statuswas determined by 16S rDNA sequencing and phylogenetic analysis. The growth-promoting characteristics ofthe strain and exopolysaccharide were evaluated through inoculation tests.【Result】 Three strains of exopolysaccharides‐ producing PGPR were identified from the rhizosphere of the two plants. Among them，strains NAHP4 andPBRS1 were notable for their high exopolysaccharides production，with levels of 1 462. 50 and 1 337. 50 mg/L，respectively.This strains exhibited growth ‐promoting properties，including nitrogen fixation and inorganic phosphorussolulisation. Exopolysaccharides promoted seed germination and seedling growth of Elymus sibiricus，through highconcentration of exopolysaccharides significantly inhibited radicle growth （P＜0. 05）. The inoculated strainsNAHP4，NBHP13 and PBRS1 lypromotedroot development in Elymus sibiricus（ P＜0. 05），with NAHP4 showingthegreatest effect.【Conclusion】 Strain NAHP4，as a high exopolysaccharide‐producing PGPR resource，has significantpotential for developing polysaccharide bacterial reagents and related products suitable for the alpine grassland ofZoige.