van Eijsden R, Díaz C L, de Pater B S, Kijne J W
Institute of Molecular Plant Sciences, Leiden University, Netherlands.
Plant Mol Biol. 1995 Nov;29(3):431-9. doi: 10.1007/BF00020975.
Legume lectin stimulates infection of roots in the symbiosis between leguminous plants and bacteria of the genus Rhizobium. Introduction of the Pisum sativum lectin gene (psl) into white clover hairy roots enables heterologous infection and nodulation by the pea symbiont R. leguminosarum biovar viciae (R.l. viciae). Legume lectins contain a specific sugar-binding site. Here, we show that inoculation of white clover hairy roots co-transformed with a psl mutant encoding a non-sugar-binding lectin (PSL N125D) with R.l. viciae yielded only background pseudo-nodule formation, in contrast to the situation after transformation with wild type psl or with a psl mutant encoding sugar-binding PSL (PSL A126V). For every construct tested, nodulation by the homologous symbiont R.l. trifolii was normal. These results strongly suggest that (1) sugar-binding activity of PSL is necessary for infection of white clover hairy roots by R.l. viciae, and (2) the rhizobial ligand of host lectin is a sugar residue rather than a lipid.
豆科植物凝集素在豆科植物与根瘤菌属细菌的共生关系中刺激根的感染。将豌豆凝集素基因（psl）导入白三叶草毛状根中，可实现豌豆共生体豌豆根瘤菌生物变种蚕豆（R.l. viciae）的异源感染和结瘤。豆科植物凝集素含有一个特定的糖结合位点。在此，我们表明，用编码非糖结合凝集素（PSL N125D）的psl突变体与R.l. viciae共同转化白三叶草毛状根，与用野生型psl或编码糖结合PSL（PSL A126V）的psl突变体转化后的情况相比，只产生了背景性假结瘤形成。对于所测试的每一种构建体，同源共生体R.l. 三叶草的结瘤都是正常的。这些结果有力地表明：（1）PSL的糖结合活性是R.l. viciae感染白三叶草毛状根所必需的；（2）宿主凝集素的根瘤菌配体是一个糖残基而非脂质。
