盐碱胁迫下产ACC脱氨酶促生菌对绿豆插条生根的作用

Effect of ACC Deaminase-Producing Bacteria on Rooting of Mung Bean Cuttings under Saline-Alkali Stress

盐碱胁迫使植物产生过量的乙烯,过量的乙烯会抑制植物生根,产1-氨基环丙烷1-羧酸(ACC)脱氨酶促生菌可以通过分解乙烯的直接前体ACC缓解盐碱对植物的伤害。为探讨盐碱胁迫下产ACC脱氨酶促生菌对植物生根的作用,从碱草根际土中筛选耐盐碱、产ACC脱氨酶能力较强的菌株,对筛选出的菌株进行鉴定,并分析了菌株对绿豆插条生根的影响。结果表明,DQJC1、DQJC5、DQJC6三个菌株产ACC脱氨酶活性分别为8.147、7.282、7.906 U/mg,3个菌株具有较强的耐盐碱能力,同时具有产吲哚乙酸(IAA)能力,经鉴定这3株细菌均属于假单胞菌属(Pseudomonas)。将3株促生菌接种到绿豆插条基部,结果发现,不论是在正常条件下还是盐碱胁迫条件下,绿豆插条的根长、鲜质量及发根数均不同程度增加;在盐碱胁迫条件下,接种3株菌显著下调了绿豆插条根中ACC合酶及ACC氧化酶活性,DQJC1和DQJC6菌株显著下调了绿豆插条根中ACC含量。说明产ACC脱氨酶促生菌通过减少乙烯的生成有效地缓解了盐碱胁迫对绿豆插条生根的抑制。

Saline-alkali stress makes plants produce excessive ethylene,which will inhibit plant rooting,and ACC(1-amino cyclopropane 1-carboxylic acid)deaminase-producing growth-promoting bacteria can alleviate the damage of saline-alkali stress to plants by breaking down the direct precursor ACC of ethylene.In order to explore the role of ACC deaminase-producing bacteria in plant rooting under saline-alkali stress,we screened and identified the strains with strong saline-alkali tolerance from alkaline grass root soil,and analyzed the effect of the strains on rooting of mung bean cuttings.The results showed that DQJC1,DQJC5 and DQJC6 strains produced ACC deaminase with activities of 8.147,7.282 and7.906 U/mg,respectively.Three strains had strong salinity-alkalinity tolerance and IAA(indoleacetic acid)production ability,which were identified to belong to Pseudomonas.Three strains were inoculated into the base of mung bean cuttings,and it was found that the root length,fresh quality and root number of mung bean cuttings were increased under normal condition and saline-alkali stress condition.Under saline-alkali stress,the three strains significantly down-regulated the activities of ACC synthase and ACC oxidase in mung bean cutting roots,and the DQJC1 and DQJC6 strains significantly down-regulated the ACC content in mung bean cutting roots,indicating that ACC deaminase-producing bacteria effectively alleviated the inhibition of saline-alkali stress on the rooting by reducing the production of ethylene.