基于根瘤菌来源的ACC脱氨酶基因提高大豆和紫云英根瘤菌的竞争结瘤能力

Improvement of competitive nodulation ability of Mesorhizobium huakuii and Sinorhizobium fredii based on the ACC deaminase gene of Bradyrhizobia

根瘤菌的竞争结瘤能力提高对提高接种剂的应用效果至关重要.为提高根瘤菌的共生固氮和竞争结瘤能力,从大豆慢生型根瘤菌USDA110中扩增1-氨基环丙烷-1-羧酸脱氨酶(ACC脱氨酶)基因和其上游调控序列,通过两亲本接合转移导入华癸中慢生根瘤菌7653R、大豆快生型根瘤菌HH103和SMH12,构建含有ACC脱氨酶的重组根瘤菌.结果显示:在土壤盆栽条件下,接种导入ACC脱氨酶的重组菌7653R,宿主植物地上鲜重、瘤数、瘤重和固氮酶活均显著增加,竞争结瘤能力提高22.6%;接种重组菌HH103,植物地上鲜重、瘤重和酶活显著增加,瘤数增加,竞争结瘤能力提高28.9%;接种重组菌SMH12,植物地上鲜重、瘤数、瘤重和酶活增加,未到达显著性,但竞争结瘤能力提高25.4%.本研究表明构建的3个重组根瘤菌具有良好的共生固氮和竞争结瘤能力,可作为有潜力的优良菌株应用到田间试验.

The competitive nodulation ability of rhizobium is essential for improving the application effect of inoculants.In this study,to improve the symbiotic nitrogen fixation and competitive nodulation ability of rhizobium,the 1-aminocycopropane-1-carboxylate(ACC)deaminase gene and its upstream regulatory sequences from Bradyrhizobium japonicum USDA110 were introduced into Mesorhizobium huakuii 7653R,Sinorhizobium fredii HH103,and SMH12 to construct a recombinant rhizobia containing ACC deaminase using the two parental conjugations.Under soil potting conditions,the results showed that astragalus inoculated with recombinant 7653R containing ACC deaminase significantly increased the fresh weight of the aerial part,nodule number,nodule weight,and nitrogenase activity.The competitive nodulation ability was increased by 22.6%.In soybean inoculated with recombinant HH103,there was a significant increase in the fresh weight of the aerial part,nodule weight,nitrogenase activity,and nodule number.The competitive nodulation ability was increased by 28.9%.Inoculation with recombinant SMH12 increased the fresh weight of the aerial part,nodule number,nodule weight,and nitrogenase activity.There was no significant increase;however,the competitive nodulation ability was increased by 25.4%.The three recombinant rhizobia strains in this study have good symbiotic nitrogen fixation and competitive nodulation ability and can be applied in field trials as potentially excellent strains.