豆科树种根部解剖结构和化学物质与结瘤的关系

【作者】 张洪娟；

【导师】 韩正敏；

【作者基本信息】 南京林业大学 ， 森林保护学， 2004， 硕士

【摘要】 自1886年德国学者Hermann Hellriegel首次发现大豆的根瘤具有固氮功能，1888年荷兰人首次分离获得根瘤菌的纯培养以来，有关豆科植物—根瘤菌共生体系的研究日益增多，成为当今世界上最活跃的研究领域之一。多年来，人们在固氮生物学，生物化学和遗传学研究均有了许多重要进展。但对非结瘤豆科树种不能结瘤固氮原因的研究较少。本文从根系的外部形态、根部解剖结构以及根内所存在的抑菌化学物质等方面对非结瘤豆科树种不能结瘤固氮的原因作了初步探讨，主要研究结果如下： 1．22个豆科树种(含羞草亚科3属，蝶形花亚科2属，苏木亚科3属)，用水培和盆栽的方法观察根的外部形态与结瘤的关系，结果表明：选取的含羞草亚科和蝶形花亚科中的树种结瘤，而苏木亚科中的树种都不结瘤。结瘤与非结瘤豆科树种的根系外形存在明显差异。非结瘤豆科树种的根系外形都是坚实如铁丝，呈深褐色至黑色；而结瘤豆科树种的根系外形较软，颜色较浅呈乳白色至土黄色。结瘤豆科树种的根瘤大小、形状、颜色有所不同，但部位相同都以侧根结瘤为主。根系的发达程度与是否结瘤没有相关性。 2．根毛的多少与豆科植物是否结瘤没有十分密切的关系。非结瘤豆科树种的侧根都没有根毛，主根都具有比较浓密的根毛；接菌苗与对照苗无区别，根毛都没有弯曲形变。结瘤豆科树种的根毛接菌前后形变比较明显，特别是侧根根毛，接菌后根毛弯曲形变；有的树种对照苗的侧根没有根毛，接菌后侧根基部具较多弯曲形变的根毛(例如合欢)。说明根瘤菌对有些结瘤豆科树种的根毛具有诱导作用。 3．以1cm左右的侧根(对照苗)为实验材料，通过石蜡切片显微镜观察，结果表明非结瘤豆科树种与结瘤豆科树种在根的表皮部分存在明显差异。非结瘤豆科树种的表皮细胞坚硬，切片完整；结瘤豆科树种的表皮细胞柔软，容易收缩破损。非结瘤豆科树种的表皮细胞外切向壁都呈现黑色，结瘤豆科树种表皮细胞外切向壁无色。非结瘤豆科树种的表皮细胞外切向壁的厚度平均4.8微米，结瘤豆科树种平均1.1微米。 4．选取饱满有活力的结瘤与非结瘤的豆科树种的种子在试验田中播种，5个月后取根并提取根内的单宁，用分光光度法测定单宁含量。结果表明，非结瘤豆科树种的根含有单宁，结瘤豆科树种的根不含有单宁，说明根内是否含有单宁是豆科植物能否结瘤的原因之一。 5．在各豆科植物的培养液中加入根瘤菌，一段时间后测定细菌在培养液中的增殖情况。结果表明结瘤豆科树种和非结瘤豆科树种的培养液中，根瘤菌的增殖没有明显差别。用不同浓度的单宁在平板上测定对根瘤菌的抑制作用，显示即使高达8％的单宁，在平板上也没有抑菌圈出现，说明单宁虽然对其他细菌有抑制作用，但对根瘤菌没有明显的效果。更多还原

【Abstract】 Since the German scholar, Hermann Hellriegel firstly studied the rhizobia of the soybean having nitrogen fixation in 1886 and the Dutch separated and obtained the pure culture of rhizobia originally in 1888, there were more and more research about the symbiosis of the legume-rhizobia, and it becomes one of the most active research fields in the world now. For many years, people have got great important research achievements in biological nitrogen fixation, biochemistry and the genetics, but there is little research on the program about non-nodule legume. With the comparison on the morphology, anatomy and the anti-germ chemical extracted from the root between the nodule and non-nodule legume, this article has studied and discussed the possible reasons why the non-nodule legume cannot nodulate. The main results were as follow:22 species of legume were selected from legume (3 genera from Mimosoideae, 2 genera from Papilionideae and 3 genera from Caesalpinioideae) and cultivated in water and pots respectively. The relationship between the morphological variation of the root and their nodulation were studied. The results indicated that the species of legume from Mimosoideae and Papilionideae can nodulate, while the species of legume from Caesalpinioideae can not nodulate. There were distinctive differentiation of the root morphology existed in the nodule legume and the non-nodule ones. The roots of non-nodule legume species are messiness, wiriness and dark brown to black in colors, however, the roots of nodule legume species are all soft and ivory to earth yellow in colors. Although the root nodule’s size, shape and the color were different, the position where the nodules form (mostly in lateral roots) was same. It also showed that the nodulation of the legume had no relation to the extent of the root’s development.The number of the root hair of the legume had no close relation to the nodulation. On the non-nodule legume species, bushy root hairs develop on the main roots, but no root hair on lateral roots. There is no difference between the inoculated seedlings and the control and root hairs didn’t crook to deform on them. On the nodule legume, however, root hairs changed greatly after inoculated, especially the lateral roots hair. Even on some species (for example Albizia julibrissiri), root hairs did not develop at the no inoculated seedlings, but more deformed roots developed on the lateral root base at the inoculated seedlings. All the things showed that the rhizobia could induce the root hairs on the lateral roots of some legume species.Taken one part about 1 cm of the control seedlings’ lateral root as the experimentmaterial, olefin slice were be tailored. The anatomic structure of this roots was observed using the microscope. The results showed that epidermal cells of the nodule legume’s root were different to the non-nodule legume’s. First, The epidermal cells of non-nodule legume species were hardness and kept full after slice up. The epidermal cells of nodule legume species, however, were soft and easy by damaged. Second, the cuter tangential wall of the epidermal cells of non-nodule legume were black, but nodule legume’s were tint or without blackness. Finally, The average thickness of cuter tangential wall of epidermal cells of non-nodule legume were 4.8 m, however, the thickness of nodule legume’s were 1.1 m on the average.Selected plump and vigorous seeds of the non-nodule legume and nodule legume respectively and planted them in the test fields and pull out them after five months. Tannin was extracted from the root and was quantitative analysis using the ultraviolet spectra-photometric. The results showed that there were some tannin in the root of non-nodule legume plant, but not any tannin in the root of nodule legume. It showed that tannin was one of the factors to affect the legume nodulation.Added the suspension of nodule bacteria to culture liquid of legume plant, the multiplication was tested after culturing a period. The result showed that the multiplication rates of bacteria were no di更多还原