藿香内生细菌HX-2的鉴定、耐性及对宿主植物的促生作用

Identification,tolerance to abiotic stress and host plant effects of endophytic bacteria HX-2 from Agastache rugosa

为开发微生物资源,给藿香丰产栽培技术提供理论依据。以从藿香健康叶片中分离的内生细菌HX-2为研究对象,结合形态学观察和16SrDNA基因序列分析,确定其归属;采用体外和体内实验相结合的方法,研究了菌株HX-2产吲哚乙酸、溶磷、盐碱和重金属铜耐性能力以及对宿主藿香种子萌发和幼苗生长的影响。结果表明,菌株HX-2为巨大芽孢杆菌(Bacillus megaterium),能分泌吲哚乙酸和溶解无机磷,在pH为5.0~9.0、NaCl含量为0.5%~8.0%、铜含量为0~6mmol·L-1的条件下能生长。接种HX-2能使藿香种子的发芽势、发芽率以及藿香幼苗的株高、根长、叶面积、鲜重、干重、叶绿素含量和根系活力显著提高22.59%,17.95%,17.08%,18.23%,14.68%,22.79%,24.95%,10.04%和19.20%,茎粗提高10.42%。内生细菌HX-2是兼具分泌吲哚乙酸和溶磷能力且有一定盐碱及重金属铜耐性的促生菌,有被进一步开发成微生物菌肥用于农业生产的巨大潜力。

To identify microbial resources and provide a theoretical basis for high-yielding Agastache rugosa crops,an endophytic bacteria,HX-2,was isolated from healthy leaves of A.rugosa and identified through morphological observation and 16 SrDNA sequence analysis.Indole acetic acid production,phosphate solubilization,salt and copper tolerance,and the effects on seed germination and seedling growth of A.rugosa were assessed in vitro and in vivo.The isolated bacterium was identified as Bacillus megaterium which is able to produce indole acetic acid and dissolve inorganic phosphorus.It was tolerant of pH's ranging from 5.0 to 9.0,0.5%to 8% NaCl and 0 to 6 mmol·L-1 Cu2+.After inoculation with HX-2,seed germination energy,seed germination percentage,seedling height,root length,leaf area,seedling fresh and dry weights,chlorophyll content,root vigor and stem diameter of A.rugosaimproved by 22.6%,18.0%,17.1%,18.2%,14.7%,22.8%,25.0%,10.0%,19.2% and 10.4%,respectively(P<0.05).These results suggest that HX-2 is a growth promoting bacteria which can be developed as a microbial fertilizer for agricultural production.