紫云英根瘤菌结瘤因子的初步研究

最近的研究结果表明,豆科植物与根瘤菌的共生识别是一种双向的信号物质交换过程.首先是豆科植物的根或种子分泌类黄酮物质,诱导根瘤菌的结瘤基因(nod genes)产生结瘤因子(nod factors),分泌到胞外,为植物所接受,从而引发植物某些基因表达,细胞分化,细胞壁形成,最终导致根毛变形等一系列变化.已经测定了几种苜蓿根瘤菌(Rhizobium meliloti)和豌豆根瘤菌(R.leguminosarum bv.viciae)结瘤因子的分子结构式,它们均属于寡糖胺类物质,在没有根瘤菌存在的条件下,结瘤因子能独立地促使根毛发生变形,这是检测结瘤因子是否存在的重要手段,即根毛变形试验(Root hairdeformation assay,简称Had试验).高浓度的结瘤因子甚至能诱导植物产生空瘤,其组织结构与典型的根瘤相同.

THE PRIMARY STUDY ON THE NOD FACTOR OF RHIZOBIUM HUAKUII

In the course of the symbiotic interaction between Rhizobium meliloti, R. leguminosarum bv. viciae and their host plants, the plant exudate can induce rhizobia produce extracellular molecules, i. e. the nod factors which cause some morphological, physiological and genetic changes in the roots of host plants. The Nod factors can be detected by the Had assay which is based on the root hair morphological changes. The result of Had assay demonstrats that at the presence of plant seed exudates, R. huakuii could produce Nod factor and its bio-activity is to elicit the root hair helix-curling.