【摘要】 为发掘多功能、作用高效的耐低温根际促生菌（PGPR）菌株，以白菜型冬油菜‘陇油7号’根际土壤为研究材料，通过平板划线法分离可培养根际菌株，并根据形态特征及16S rRNA基因确定其分类地位，评价其抗逆性、产酶和生理生化特性以及促生效果。结果表明：从‘陇油7号’根际土壤筛选出命名为a-1、c、c-1、d、h、j和z的7株PGPR，其中4株具解钾能力，3株具产铁载体。进一步分析发现，h菌株解钾能力最好，其溶钾量高达217.16 mg/L,c-1菌株产铁载体能力最强，可溶性指数（D/d值）达3.43；分离的7菌株中，仅a-1菌株溶无机磷，其D/d值为1.53。分析菌株的产酶特性发现，j、c、h和z菌株分别具有较强的产果胶酶、纤维素酶、蛋白酶和淀粉酶的能力，其D/d值分别为3.23、3.29、2.55和4.14；对菌株抗逆性分析发现，a-1、h和z菌株在聚乙二醇-6000质量浓度25%（水势为-0.73 MPa）干旱胁迫下生长状态较好，c、c-1和d菌株的耐盐（NaCl）质量浓度可达8%～10%,a-1、c-1和h菌株可耐低温（4℃）；促生试验结果表明，3株耐低温（4℃）菌株均对冷敏感白菜型冬油菜‘天油4号’种子的萌发有促生作用，其中c-1菌株促生效果最佳，其胚芽、胚根的长度分别增加了27.68%和38.04%；利用16S rRNA基因序列同源性分析鉴定菌株结果表明，a-1和h菌株为假单胞菌属（Pseudomonas）,c-1菌株为近芽孢杆菌属（Peribacillus）,d菌株为微杆菌属（Microbacterium）,j菌株为尼尔菌属（Niallia）,z菌株为芽孢杆菌属（Bacillus）。综上所述，从白菜型冬油菜‘陇油7号’根际土壤中筛选出的a-1、c、c-1、d、h、j和z菌株具解钾、产酶、耐干旱和耐盐胁迫等多种功能，且耐低温菌株有不同程度的促生效果。该研究结果丰富了白菜型冬油菜菌种资源，为冬油菜的抗寒栽培提供理论依据。更多还原

【Abstract】 In order to explore multi-functional and high-effective low-temperature-tolerant and plant growth promoting rhizobacteria(PGPR)strains,the study isolated culturable PGPR strains from the rhizosphere soil of‘ Longyou 7’ winter turnip rape varieties by plate streaking method. The taxonomic status of these strains was determined according to morphological characteristics and 16S rRNA gene,and the stress-tolerance,enzyme production characteristics,physiological and biochemical characteristics as well as growth-promoting effect of these strains were further evaluated. The results indicated that 7 PGPR strains named a-1,c,c-1,d,h,j and z were screened from the rhizosphere soil of‘ Longyou 7’. Among them,4 strains had the potassium solubilizing capacity,and 3 strains had the siderophore producing ability. Further analysis showed that strain h had the best potassium solubilizing capacity,and it could dissolve potassium up to 217.16 mg/L. Strain c-1 had the strongest siderophore producing ability,and its soluble index(D/d value)was 3.43. Among the 7 strains,only a-1 strain dissolved inorganic phosphorus,and its soluble index was 1.53. The strain j,c,h and z had strong ability to produce pectinase,cellulase,protease and amylase,and their D/d values were 3.23,3.29,2.55 and 4.14,respectively. Strains a-1,h and z grew well under drought stress with 25% PEG-6000(-0.73 MPa water potential). Strains c,c-1 and d could tolerate 8%-10% NaCl concentration,and strains a-1,c-1 and h could tolerate low temperature at 4℃. The results of the growth-promoting test showed that three low-temperature-tolerant strains(a-1,c-1 and h)had a growth-promoting effect on the germination of cold-sensitive winter rapeseed seeds‘ Tianyou 4’,and the strain c-1 had the best growth-promoting effect. The length of embryo and radicle of‘ Tianyou 4’ increased by 27.68% and 38.04%, respectively. The identification of PGPR strains using 16S rRNA gene sequence homology analysis determined that strains a-1 and h,c-1,d,j and z were Pseudomonas,Peribacillus,Microbacterium,Niallia,and Bacillus,respectively. In conclusion,PGPR strains screened from ‘Longyou 7’ PGPR strains had various functions such as potassium solubilization,enzyme production,drought tolerance and salt stress,and the low-temperature-tolerant strains had growth-promoting effects. Therefore,PGPR strains detected in this study enriched the bacterial resources of winter rapeseed,and provided technical and theoretical support for the cold-tolerant cultivation of winter turnip rape.更多还原