Regulation of the expression of the nod box-independent nodulation gene, nolX, in Sinorhizobium fredii, a nitrogen-fixing symbiont of legume plants
Regulation of the expression of the nod box-independent nodulation gene, nolX, in Sinorhizobium fredii, a nitrogen-fixing symbiont of legume plants
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DOI：
10.1111/j.1574-6968.1997.tb12746.x
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发表时间：
1997-12-01
影响因子：
2.1
通讯作者：
Krishnan, HB
中科院分区：
文献类型：
--
作者：
Bellato, CM;Pueppke, SG;Krishnan, HB
nolX是来自固氮共生菌费氏中华根瘤菌（Sinorhizobium fredii）的一个非结瘤盒依赖的促生长基因，它调控大豆的品种特异性促生长。该基因的表达是由宿主根中的植物信号素触发的，但不是由典型的顺式作用节点盒启动子介导的。我们已经发现，两种黄酮类化合物，大豆苷元和香豆雌酚，诱导表达的nolX-lacZ基因融合在pH值5.5和8.5之间，最佳在6.5。nolX的表达高度依赖于营养状况，但对盐度不敏感。methylethane和酪蛋白氨基酸，修正案，提高了hrpF的表达，同源基因从植物病原体野油菜黄单胞菌生物变种vesicatoria，有没有和强烈的负面影响，分别对nolX的表达。S.的生长与标准酵母提取物-甘露醇培养基相比，Fredii以鼠李糖、半乳糖、木糖或肌醇作为碳源大大提高了诱导率。然而，没有一个测试的变量，释放nolX从其依赖于作为诱导剂的多巴胺。
nolX, a nod box-independent nodulation gene from the nitrogen-fixing symbiont, Sinorhizobium fredii, regulates cultivar-specific nodulation of soybean. Expression of this gene is triggered by isoflavonoid cues from host roots but is not mediated by a typical cis-acting nod box promoter. We have found that two isoflavonoids, daidzein and coumestrol, induce expression of a nolX-lacZ gene fusion at pH values between 5.5 and 8.5, with an optimum at 6.5. Expression of nolX is highly dependent on nutritional status but insensitive to salinity. Methionine and casamino acids, amendments that enhance expression of hrpF, a homologous gene from the plant pathogen Xanthomonas campestris biovar vesicatoria, have no and strongly negative effects, respectively, on expression of nolX. Growth of S. fredii on rhamnose, galactose, xylose, or myo;inositol as carbon source greatly elevates inducibility in comparison to a standard yeast extract-mannitol medium. None of the tested variables, however, released nolX from its dependence on isoflavonoids as inducers.