高寒草地优势植物根际细菌促生特性及初步鉴定

Characteristic analysis and preliminary identification of plant growth-promoting rhizobacteria of dominant plants in alpine grassland

筛选获得能促进高寒草地退化植被生长的优良耐低温植物根际促生细菌(PGPR),能够丰富高寒草地优良菌株资源库。本研究以前期分离的18株细菌菌株为研究对象,采用乙炔还原法、钼锑抗比色法、Salkowski比色法和平板对峙法分别检测了18株菌株的固氮、溶磷、分泌植物生长激素(IAA)和抑制植物病原真菌的能力。结果表明:有14株菌均具有固氮、溶磷、分泌IAA特性,其中固氮酶活性为25.43~230.52nmol·(h·mL)^(-1),溶有机磷量为66.90~115.06μg·mL^(-1),溶无机磷量为9.22~380.28μg·mL^(-1),分泌IAA量为12.45~71.71μg·mL^(-1)。其中2株菌编号为LMG2、LMJ2拮抗病原菌锐顶镰孢菌(Gibberella acuminata)效果显著,对其抑制率分别为30.75%和31.00%。综合比较各菌株特性,筛选出6株优良PGPR进行16S rRNA基因序列比对分析以确定其分类地位。经鉴定:菌株LMG2和LMJ2菌株与Pseudomonas piscium P50^(T)的亲缘关系最近,菌株LMY8与Pseudomonas kairouanensis KC12^(T)的亲缘关系最近,菌株CND1与猴假单胞菌(Pseudomonas simiae Oli^(T))的亲缘关系最近,菌株LNA2、LPA7与Pseudomonas neuropathica P155^(T)的亲缘关系最近。研究筛选的6株耐低温菌株兼具多种优良特性,对高寒退化草地的植被修复具有应用潜力,可为后续制备修复高寒退化草地微生物菌剂提供优质菌株资源。

The low temperature tolerant plant growth-promoting rhizobacteria that can promote the growth of degraded vegetation in alpine grassland were screened and obtained.This can enrich the resource base of high quality strains found in alpine grassland.Based on the 18 strains isolated in a previous study,the method encompassing the acetylene reduction method,molybdenum antimony anti-colorimetric method,Salkowski colorimetric method and plate standoff method,respectively,nitrogen fixation,phosphorus solubilization,IAA secretion,and antagonism to phytopathogenic fungi were measured.The results showed that 14 strains of the 18 strains that screened had nitrogen fixation,phosphorus solubilization and IAA secretion,in which the nitrogen fixing enzyme activity ranged from 25.43 to 230.52 nmol·(h·mL)^(-1).Organic phosphorus solubilization ranged from 66.90 to 115.06μg·mL^(-1),the inorganic phosphorus solubilization ranged from 9.22 to 380.28μg·mL^(-1),and the amount of IAA secretion ranged from 12.45 to 71.71μg·mL^(-1).Two of the strains antagonized the pathogen Gibberella acuminata with significant effect.The inhibition rates against the pathogenic fungus G.acuminata were 30.75% and 31.00%,respectively.The characteristics of the strains were compared,and six high quality PGPR strains were screened for 16S rRNA sequence comparison to determine their taxonomic status.The strains LMG2 and LMJ2 were identified as the closest relatives to Pseudomonas piscium P50T,LMY8 as the closest relatives to Pseudomonas kairouanensis KC12T,CND1 as the closest relatives to Pseudomonas simiae OliT,and strains LNA2 and LPA7 as the closest relatives to Pseudomonas neuropathica P155T.The six low-temperature-tolerant strains screened in the study have a variety of high quality characteristics and have the potential to be applied to the vegetation restoration of alpine degraded grassland,and can provide high quality strain resources for the subsequent preparation of microbial agents for the restoration of alpine degraded grassland.