ELUCIDATION OF MECHANISM ASSOCIATED WITH THE FORMATION OF SYMBIOTIC NITROGEN FIXING SYSTEMS AND DEVELOPMENT OF NITROGEN FIXING ACTIVITY IN LEGUMINOUS PLANT.

根据大豆根瘤菌的寄主专一性和大豆对根瘤菌的喜好，从RJ_2品种种子中提取了与RJ_2亲和菌株凝集和生长刺激的凝集素。从野生大豆和栽培大豆中分离到的根瘤菌可分为3个节群，每个节群对应于每种寄主植物。寄主特有的过程似乎是侵染线的形成，而不是根瘤菌的附着。含有来自豆类根瘤杆菌的结瘤基因片段的质粒。将Lac操纵子和Tn5基因转入弗氏酵母中。在接合子CT24中，常见的结瘤基因干扰了费氏根结杆菌的结瘤基因，导致大豆结瘤不良。研究了豌豆种子和根部分泌物对豌豆结瘤的影响，并鉴定了其中的黄酮类化合物。根中硝态氮的吸收迅速转移到地上部，几乎不进入根瘤。去除发育中的豆荚降低固氮活性是由于根瘤中固定氮的去除减少所致。感染细胞和未感染细胞具有共同的固氮过程，前者检测到黄嘌呤氧化酶和苹果酸脱氢酶，后者主要检测到CO_2固定酶、尿酸酶和氨基酸合成酶。大豆根瘤中的尿酸酶是一种结瘤蛋白，对其特征进行了检测，发现子叶中含有一种尿酸酶，该酶与针对该根瘤尿酸酶产生的抗体发生交叉反应。分离和鉴定了代表大豆根瘤发育早期表达基因的新的结瘤蛋白基因。

In relation to host specificity of soybean rhizobia and preferences of soybean for rhizobia, the lectin agglutinating and growth-stimulating the compatible bacterial strain with the Rj_2-cultivar was extracted from seeds of Rj_2 cultivar. The isolated rhizobia from wild and cultivated soybeans and sairatro were classified into 3 nod-groups which corresponded to each host plant. Host specific process was seemed to be the formation of infection thread and not the attachment of rhizobia. The plasmid which has a fragment containing nodulation genes from R. leguminosarum. lac operon and Tn5 were transferred into R. fredii. In the transconjugant CT24, common nod genes interfere with R. fredii nod genes, causing poor nodulation in soybean. Effects of exudates from seeds and roots of cowpea on nodulation for cowpea were examined, and flavonoid commpounds were identified. Nitrate nitrogen uptake in roots was transferred rapidly into the shoots, and hardly transaferred into nodules. The reduction of nitrogen fixing activity by removal of developing pods was due to reduction of removal of fixed nitrogen from nodules. Infected and uninfected cells shared nitrogen fixing process, xanthine oxidase and malate dehydrogenase were detected in the formers, and CO_2 fixing enzyme, uricase and amino acid synthesizing-enzyme were revealed mainly in the latters. One of nodulins, uricase in soybean nodule were examined for the characteristics, and cotyledons were shown to contain a uricase that cross-react with antibodies raised against the nodule uricase. Novel nodulin cDNAs representing genes expressed at early stages of soybean nodule development were isolated and chracterized.