沙地柏根际促生耐寒短杆菌SDB5的分离和功能鉴定

Isolation and Functional Identification of Growth-promoting Rhizobacteria Brevibacterium frigoritolerans SDB5 from Sabina vulgaris

从沙地柏根中分离到1株根际促生菌,并对其特征进行鉴定。为明确其功能,以水稻为试验材料,用梯度Na_(2)CO_(3)模拟盐碱胁迫,研究该菌对水稻种子萌发及生理指标的影响;并在盐碱地中研究该菌对水稻农艺性状的影响。结果显示:(1)该菌为杆状,菌落呈白色,革兰氏阳性,长约2667nm,宽约906.7nm,16SrDNA测序表明,其属于耐寒短杆菌属,命名为SDB5(Brevibacterium frigoritolerans SDB5)。菌体内生长素含量为356.90ng/g,细胞分裂素主要是异戊烯基腺苷和异戊烯基腺嘌呤,含量分别为2.13ng/g和48.57 ng/g。该菌能在0~1mol/L的NaCl或pH6~11的培养基上正常生长。盐碱复合胁迫与上述单独胁迫结果类似,说明SDB5菌有耐盐碱能力。(2)在梯度Na_(2)CO_(3)模拟盐碱胁迫下,该菌能使水稻种子萌发率提高15.2%,叶片中叶绿素含量、过氧化氢酶活性和脯氨酸含量分别提高90%、95%和73%,说明SDB5菌能提高水稻的耐盐碱性。(3)在土壤含盐量0.22%、pH8.4的盐碱地上,该菌能使水稻出苗率提高20%,穗基直径增粗48%,穗长增加12.4%,根长增加43%,根面积增加34.8%,根体积增加25.7%,说明SDB5菌能促进水稻的生长;穗实粒数显著增加,理论产量增加18.2%。综上,耐寒短杆菌SDB5可以提高水稻的种子萌发率及植株耐盐碱性,并在轻度盐碱地中使水稻的生长势增强,产量提高,在农业生产上有重要意义。

A plant growth-promoting rhizobacteria was isolated from the roots of Sabina vulgaris andits characteristics were identified.The rice was used as experimental material to specify its function,the effect of the strain on rice seed germination and physiological indexes was analyzed by simulatingsaline alkali stress with gradient Na_(2)CO_(3),meanwhile,the effect of the strain on agronomic charactersin saline-alkali soil was also studied.The results indicated that:(1)the bacterium was rod-shaped andits bacterial colony was white.It was gram-positive,and its length was about 2667 nm and its widthwas about 906.7 nm.16S rDNA sequencing showed that the bacterium belonged to the genus Brevibacterium frigoritans,which was specifically named as Brevibacterium frigritolerans SDB5.Theauxin content within the strains was 356.90 ng/g.The cytokinins were mainly isoprenyl adenosineand isoprenyl adenine,which were 2.13 ng/g and 48.57 ng/g,respectively.The bacterium couldgrow normally in NaCl medium with concentrations of 0-1 mol/L or medium with pH 6-11.The results of saline-alkali combined stress were similar to those individual stresses above,indicating that SDB5 strain had saline-alkali tolerance.(2)Under the simulated saline alkali stress of gradient Na_(2)CO_(3),the strain increased the germination rate of seeds by 15.2%.Meanwhile,the chlorophyllcontent,catalase activity,and proline content in leaves increased by 90%,95%and 73%.respective-ly,indicating that SDB5 could improve the saline-alkali tolerance of rice.(3)On the saline-alkali landwith soil salt content of 0.22%and pH 8.4,the strain increased the seedling emergence rate of rice by20%,the diameter of panicle base by 48%.the panicle length by 12.4%,the root length by 43%,the root area by 34.8%and the root volume by 25.7%,it was proved that SDB5 strain could promotethe growth of rice.The number of grains per panicle increased significantly,and the theoretical yieldincreased by 18.2%.In summary,Brevibacterium frigoritolerans SDB5 can improve the germinationrate of rice seeds,the saline-alkali tolerance of plants,and enhance the growth potential and yield ofrice in mild saline-alkali soil,which is of great significance in agricultural production.