MONITORING OF RHIZOBLA ON THE ROOT SYSTEM AND ANALYSIS OF THE MECHANISM OF NODULATION IN SOME LEGUMES USING A GUS MARKED STRAIN

利用一种气体标记菌株，研究了根瘤菌对某些豆科植物侵染过程的多样性。结果总结如下：1。获得USDA3024、b.p sp.慢生根瘤菌的gus标记菌株。用含有β-葡萄糖醛酸酶操纵子（mTn5SSgusA21 on pCAM121）的质粒与大肠杆菌S17-λ pir进行了偶联实验。在X-Gluc缓冲液中培养，各标记菌株形成的根瘤呈现蓝色。标记菌株的结瘤能力和各豆科植物的氮酶活性与亲本无显著差异。生长袋法是一种适合于绿萝幼苗中有气体标记菌株感染试验的方法。4 .显微镜观察发现，在生2 d的黄爪草（Crotalaria juncea）幼苗的丝状根毛上有侵染丝状结构。在培养液中施用硝酸盐对花生根瘤数和氮酶活性有抑制作用。7.山田菁茎节起源于子叶节部位，随后在茎表面形成。目前正在利用gus标记菌株进一步研究根瘤菌感染过程的多样性以及不同环境条件对结瘤和固氮的影响。另一种标记基因GFP也将用于这些实验。

The diversity in the infection process of rhizobia to some legumes was investigated by using a gus-marked strain. The results are summarized as follows.1. To obtain gusA-marked strains of Bradyrhizobium sp. USDA3024, B.sp. U9709-A, and Azorhizobium caulinodans U9709-SRS, conjugation experiments were performed with the strain of E.coli S17-λ pir with plasmid containing the β-glucuronidase operon (mTn5SSgusA21 on pCAM121). Root nodules formed by each gus-marked strain developed blue color on incubation in X-Gluc buffer in Clotalaria, Arachis and Sesbania.2. The gus-marked strain did not differ from the parent strain in nodulation capability and nitrogenase activity in each legume.3. Growth pouch method was adequate for infection test of a gus-marked strain in Crotalaria seedling.4. With a microscopic observation, an infection thread-like structure was found in the root hairs of tap root in 2 day-old seedling of Crotalaria juncea.5. Number of root nodule and nitrogenase activity in peanut plants were inhibited by application of nitrate to culture solution.6. Stem nodules of Sesbania rostrata were initiated at the site of the cotyledonary node and followed by forming on the surface of stem.7. Further investigation of the diversity in the rhizobia-infection process and the effect of various environmental conditions on nodulation and nitrogen fixation is now in progress using the gus-marked strain. Another marker gene, GFP, would be also used for those experiments.