导入dctABD和nifA基因对费氏中华根瘤菌共生固氮的影响研究

以pTR102为载体构建重组质粒pHN307，其上克隆有来自昔蓿中华根瘤菌（Sinorthizobium meliloti）的四碳二羧酸转移酶基因dctABD、来自肺炎克氏杆菌(Klebsiella pneumoniae）的nifA基因和来自pDB30所含的发光酶基因lux-AB。经三亲本接合转移，将pHN307导入费氏中华根瘤菌（S.fredii)NH01、YC4和GR3，并考察了转移接合子中pHN307在传代培养和共生条件下的稳定性。与出发菌相比较的植物盆栽试验结果表明，在与大豆黑农33共生时，导入pHN307后的转移接合子均可显著提高结瘤植株的瘤重、地上部分干重和地上部分总氮量。在与大豆川早一号共生时，转移接合子HN01（pHN307）可显著提高结瘤植株的瘤数和瘤重；GR3（pHN307）可显著提高结瘤植株的瘤数、瘤重、地上部分干重和地上部分总氮量；导入pHN307的YC4却呈现出负作用。本研究表明，导入dctABD可提高固氮效率

A Study of the Effects on the Symbiotic Nitrogen Fixation of Sinorhizobium fredii with the Introduction of dctABD and nifA Genes

A recombinant plasmid pHN307 containing C 4 dicarboxylic acid transport genes ( dctABD ) from Sinorhizobium meliloti,nifA genes from Klebsiella pneumoniae and reporter genes luxAB from pDB30 was constructed by using pTR102 as the vector. The pHN307 was then introduced into the S. fredii HN01,YC4 and GR3 by tri parental mating,and the stability of pHN307 in the transconjugants under free living and symbiotic condition was also investigated. The results of plant pot experiment indicated that the introduction of pHN307 in the transconjugants could significantly increase the nodule fresh weight,shoot dry weight (biomass) and total nitrogen content of the symbiotic plants with soybean variety of Heilong 33. When the transconjugants were in symbiotic with soybean variety of Chuanzao No.1,HN01 (pHN307) could significantly increase its root nodule number and fresh weight; GR3(pHN307) could significantly increase its root nodule number,nodule fresh weight,shoot dry weight and total nitrogen content,but YC4(pHN307) demonstrated negative effect under the same condition. The results of this study suggested that the introduction of dctABD and nifA could improve the symbiotic nitrogen fixation efficiency and nodulation ability of the rhizobia tested,respectively, and its effect was relevant to the characteristics of recipient rhizobia and soybean variety.