Georg-August-University Göttingen, Albrecht-von-Haller Institute for Plant Sciences, Department of Plant Biochemistry, 37077 Göttingen, Germany.
New Phytol. 2011 Jan;189(2):568-79. doi: 10.1111/j.1469-8137.2010.03504.x. Epub 2010 Oct 22.
Jasmonic acid (JA) is a plant signalling compound that has been implicated in the regulation of mutualistic symbioses. In order to understand the spatial distribution of JA biosynthetic capacity in nodules of two actinorhizal species, Casaurina glauca and Datisca glomerata, and one legume, Medicago truncatula, we determined the localization of allene oxide cyclase (AOC) which catalyses a committed step in JA biosynthesis. In all nodule types analysed, AOC was detected exclusively in uninfected cells. The levels of JA were compared in the roots and nodules of the three plant species. The nodules and noninoculated roots of the two actinorhizal species, and the root systems of M. truncatula, noninoculated or nodulated with wild-type Sinorhizobium meliloti or with mutants unable to fix nitrogen, did not show significant differences in JA levels. However, JA levels in all plant organs examined increased significantly on mechanical disturbance. To study whether JA played a regulatory role in the nodules of M. truncatula, composite plants containing roots expressing an MtAOC1-sense or MtAOC1-RNAi construct were inoculated with S. meliloti. Neither an increase nor reduction in AOC levels resulted in altered nodule formation. These data suggest that jasmonates are not involved in the development and function of root nodules.
茉莉酸（JA）是一种植物信号化合物，它参与了共生关系的调节。为了了解两种共生固氮植物（木麻黄和 Datisca glomerata）和一种豆科植物（Medicago truncatula）根瘤中 JA 生物合成能力的空间分布，我们确定了催化 JA 生物合成关键步骤的丙二烯氧化物环化酶（AOC）的定位。在分析的所有根瘤类型中，AOC 仅在未感染细胞中被检测到。比较了三种植物的根和根瘤中 JA 的水平。两个共生固氮植物的根瘤和未接种根，以及未接种或接种野生型根瘤菌（Sinorhizobium meliloti）或不能固定氮的突变体的 M. truncatula 根系，在 JA 水平上没有显著差异。然而，所有被检查的植物器官中的 JA 水平在机械干扰下显著增加。为了研究 JA 是否在 M. truncatula 的根瘤中发挥调节作用，将含有表达 MtAOC1-sense 或 MtAOC1-RNAi 构建体的根的复合植物接种根瘤菌。AOC 水平的增加或减少都不会导致根瘤形成的改变。这些数据表明，茉莉酸酯不参与根瘤的发育和功能。
