The DMI1 and DMI2 early symbiotic genes of Medicago truncatula are required for a high-affinity nodulation factor-binding site associated to a particulate fraction of roots
The DMI1 and DMI2 early symbiotic genes of Medicago truncatula are required for a high-affinity nodulation factor-binding site associated to a particulate fraction of roots
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DOI：
10.1104/pp.105.068981
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发表时间：
2006-01-01
期刊：
影响因子：
7.4
通讯作者：
Bono, JJ
中科院分区：
文献类型：
--
作者：
Hogg, BV;Cullimore, JV;Bono, JJ
苜蓿与根瘤菌共生体系的建立。而苜蓿中华根瘤菌则依赖于其配偶菌产生的硫酸化脂-壳寡糖发酵因子（Nod）。在这篇文章中，使用生物化学方法来表征植物宿主中假定的结瘤因子受体，我们描述了一个高亲和力的结合位点（Kd = 0.45 nM）的主要结瘤因子产生的S。苜蓿草。该位点被称为Nod因子结合位点3（NFBS3）。NFBS 3与从蒺藜苜蓿根制备的高密度级分相关，并显示出对脂壳寡糖结构的结合特异性。对于先前表征的结合位点（NFBS 1和NFBS 2），NFBS 3不识别S上的硫酸酯基团。苜蓿结瘤因子结瘤因子结合的早期共生突变体根提取物的研究。truncatula揭示了新位点存在于Nod因子感知中，并且不产生感染3（dmi 3）突变体，但在dmi 1和dmi 2突变体中不存在。所有这些突变体的根和细胞培养物仍然分别含有与NFBS 1和NFBS 2相似的位点。这些结果表明，NFBS3是不同的NFBS2和NFBS1，是依赖于共同的共生基因DMI1和DMI2需要建立与根瘤菌和丛枝菌根真菌的共生。这个网站在建立根内共生的潜在作用进行了讨论。
The establishment of the legume-rhizobia symbiosis between Medicago spp. and Sinorhizobium meliloti is dependent on the production of sulfated lipo-chitooligosaccharidic nodulation ( Nod) factors by the bacterial partner. In this article, using a biochemical approach to characterize putative Nod factor receptors in the plant host, we describe a high-affinity binding site (K-d = 0.45 nM) for the major Nod factor produced by S. meliloti. This site is termed Nod factor-binding site 3 ( NFBS3). NFBS3 is associated to a high-density fraction prepared from roots of Medicago truncatula and shows binding specificity for lipochitooligosaccharidic structures. As for the previously characterized binding sites ( NFBS1 and NFBS2), NFBS3 does not recognize the sulfate group on the S. meliloti Nod factor. Studies of Nod factor binding in root extracts of early symbiotic mutants of M. truncatula reveals that the new site is present in Nod factor perception and does not make infections 3 (dmi3) mutants but is absent in dmi1 and dmi2 mutants. Roots and cell cultures of all these mutants still contain sites similar to NFBS1 and NFBS2, respectively. These results suggest that NFBS3 is different from NFBS2 and NFBS1 and is dependent on the common symbiotic genes DMI1 and DMI2 required for establishment of symbioses with both rhizobia and arbuscular mycorrhizal fungi. The potential role of this site in the establishment of root endosymbioses is discussed.