干旱地区植物根际促生菌鉴定及促生和耐旱特性研究

Identification,Growth-Promoting and Drought-Tolerant Characteristics of Plant Growth-Promoting Rhizobacteria for Arid Area Plants

本试验以干旱区3种植物为材料,利用选择性培养基从植物根际分离筛选具有固氮、溶磷、分泌植物激素及耐旱的菌株,进行16S rRNA分子生物学鉴定,并通过纸上发芽试验验证菌株促生效果,以期为干旱地区专用微生物菌肥提供优良菌种资源。结果表明:从3种植物根际共分离出37株菌株,其中兼具溶磷、固氮促生特性的占35.1%,菌株固氮酶活性介于17.92~169.74 nmol C2H4/(h·mL),溶无机磷量为13.39~363.31μg/mL,溶有机磷量为58.69~99.37μg/mL。选择12株固氮、溶磷能力较好的菌株进行分泌植物激素及耐旱特性测定,发现12株菌株均能分泌吲哚乙酸且分泌量为2.86~27.60μg/mL;大部分菌株也均能分泌玉米素和脱落酸,分泌量分别为1.75~7.78μg/mL、1.98~4.61μg/mL。从中筛选出特性优良的菌株5株,经鉴定菌株YB6和HC7分别为枯草芽孢杆菌(Bacillus subtilis)和氧化微杆菌(Microbacterium oxydans),菌株HL7、HC9和HC3分别属于无色杆菌属(Achromobacter sp.)、苍白杆菌属(Ochrobactrum sp.)和叶杆菌属(Phyllobacterium sp.)。纸上发芽试验结果显示,5株植物根际促生菌既能促进种子的萌发,又能缓解干旱胁迫对种子生长的抑制作用,其中,菌株YB6和HC9对种子的萌发和生长效果较为突出,具有作为微生物肥料菌种资源在干旱区应用的潜力。

To provide high-quality strain resources for specialized microbial fertilizer applying in arid regions,strains were isolated with characteristics of nitrogen fixation,phosphorus solubilization,plant hormones secretion,and drought tolerance from plant rhizosphere by selective medium on three plant species from arid areas.16S rRNA identification was applied for molecular distinguish and effects of growthpromoting was tested by paper germination test.Results of this research revealed 35.1%of 37 strains isolated from three plant rhizospheres had the characteristics of phosphorus solubilization,nitrogen fixation,and plant growth-promoting.The nitrogenase activity of the strains ranged from 17.92 to 169.74 nmol C2H4/(h·mL).The concentration of dissolved inorganic phosphorus ranged from 13.39 to 363.31μg/mL,while dissolved organic phosphorus ranged from 58.69 to 99.37μg/mL.Twelve of the strains with better nitrogen fixation and phosphorus solubilization were picked for further testing of plant hormone secretion and drought tolerance.Secreting results demonstrated that 2.86 to 27.60μg/mL indoleacetic acid was produced by all 12 strains.Meanwhile,zeatin and abscisic acid were produced by most of the strains,with the volume of 1.75 to 7.78μg/mL and 1.98 to 4.61μg/mL,respectively.Five superior PGPR strains through phylogenetic analysis were identified:strain YB6 was Bacillus subtilis,HC7 was Microbacterium oxydans.Additionally,strains HL7,HC9,and HC3 were categorized under the genera Achromobacter sp.,Ochrobactrum sp.,and Phyllobacterium sp.,respectively.For the results of germination test on paper,five selected PGPR strains both improved seed germination and alleviated the inhibition of drought stress on seed growth.Notably,strains YB6 and HC9 had the most significant effect on seed germination and growth,indicating their potential as valuable microbial fertilizer resources in arid regions.