紫云英根瘤菌Hup°菌株吸氢与固氮  

H_2-uptake and N_2-fixation in Hup^c Strain of Rhizobium astragalus

作　　者：孙金华 陈秉俭[1] 郁宝麟 杨玉锁[1] 宋鸿遇[1] 

机构地区：[1]中国科学院上海植物生理研究所,上海200032

出　　处：《植物生理学报（0257-4829)》1991年第3期290-294,共5页Acta Phytophysiologica Sinica

基　　金：中国科学院自然科学基金;青年奖励研究基金

摘　　要：紫云英根瘤菌109菌株经NTG诱变后,选出1027,1247,1439,1675 4株菌株,其生长比野生型109菌株快,而其吸氢活性对碳底物不敏感或部分敏感,称为Hup°菌株。菌株1675和1439形成的根瘤其吸氢前的滞后时间缩短,表明内源抑制吸氢的效应缓解。经回接,1675菌株的Hup°性状较1439菌株稳定。由根瘤内分离回收的1675-1和1675-32两菌株,其共生体的吸氢与固氮活性均比菌株109高,其根瘤的耗氧量比109根瘤低,说明1675菌株有利于根瘤累积碳底物。The ability to recycle H_2 evolved by nitrogenase is thought to be of importance in improving the efficiency of nitrogen fixation and to be a factor in increasing plant yields in symbiotic or plant-bacteria associated systems. We have shown previously that the expression of hydrogenase was regulated by a number of factors, which included H_2, O_2 and C substrates, and all utilizable C substrates repressed H_2 uptake. It is likely that H_2 uptake system is subject to catabolite repression-like regulation, a phenomenon that has been linked to the regulation by C substrates and respiratory electron acceptors. The purpose of the experiments described herein was to compare the H_2 uptake activities of Hup^c mutants with that of Hup^+ wild strain in symbiotic state. The Hup^c mutants were selected on the basis of their ability to utilize H_2 as an energy source in the presence of high concentration of C substrates. Four isolates (1027, I247, 1439 and 1675) were selected from Rhizobium astragalus strain 109 after mutagenesis with N-methyl-N^8-nitro-N-nitrosoguanidine. In comparison with the parent strain the isolates had higher growth rate on YM medium (Fig. 1), and their H-uptake activities were insensitive or partially sensitive to carbon repression (Table 2). Thus, the isolates were considered to be constitutive H_2-uptake (Hup^c) strains. Nodules on Chinese milk vetch with two isolates (1439 and 1675) had shorter lag periods of H_2-uptake activities than nodules with parent strain 109 (Fig. 2). It indicated that the carbon repression effect in Hup^c mutants was alleviated when they were in symbiotic state. The Hup^c properties of reisolates from nodule were more stable in strain 1675 than in strain 1439 (Table 3). Nodules with reisolates I675—1 and 1675—32 showed higher H_2-uptake and N_2-fixation activities and lower rate of O_2-consumption than those of the parent strain 109 (Fig. 3,4,5). It was suggested that the Hup^c strain favours the accumulation of carbonhydrates in nodules.

关 键 词：紫云英 根瘤菌 Hup^c菌株 吸氢 

分 类 号：S541.301[农业科学—作物学]