Factors involved in root formation in Medicago truncatula
Factors involved in root formation in Medicago truncatula
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DOI：
10.1093/jxb/erl224
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发表时间：
2007-02-01
影响因子：
6.9
通讯作者：
Rolfe, Barry G.
中科院分区：
文献类型：
--
作者：
Imin, Nijat;Nizamidin, Mahira;Rolfe, Barry G.
生长素诱导根形成的事实已被知道超过半个世纪。然而，尽管在这一领域的最新进展，无论是生长素反应基因导致根形成的分子过程，也不是植物激素和其他生物活性分子之间的相互作用，在承诺阶段的根形成很好地理解。在这里，生物分子，如细胞分裂素，谷胱甘肽，黄酮类化合物，以及在模型豆科植物蒺藜苜蓿在体外根形成的几个转录因子的表达的影响。结果表明，生长素NAA（1-萘乙酸）预处理7天可以不可逆地中断体细胞胚的形成，而还原和氧化形式的谷胱甘肽增强根的形成，通过一种机制独立于乙烯感知，乙烯不敏感的SKL突变体的分析所确定的。还表明，槲皮素和众所周知的生长素转运抑制剂NPA（N-1-萘基邻苯二甲酰胺酸）（其具有与槲皮素类似的结构）以及槲皮素芒柄花黄素和染料木黄酮导致根形成的严重减少。此外，几个转录因子的相对表达进行了分析，在1周龄NAA处理的外植体（干细胞龛形成阶段），在NAA和BAP处理的外植体（无根形成），并在发芽种子的根。结果表明，第一次在豆科植物中，转录因子同源结构域WOX 5和AP 2-域含有PLETHORA 1和2，BABY BOOM 1强烈诱导生长素此外，而细胞分裂素除了显着降低其表达，表明这些基因在根干细胞龛的形成中的作用。
The fact that auxin induces root formation has been known for more than half a century. However, despite the recent progress in this field, neither the molecular processes in which the auxin-responsive genes leading to root formation nor the interactions between phytohormones and other bioactive molecules during the commitment phase of root formation are well understood. Here the effect of biomolecules such as cytokinin, glutathione, and flavonoids, as well as the expression of several transcription factors in in vitro root formation in model legume Medicago truncatula are presented. It was demonstrated that auxin NAA (1-naphthaleneacetic acid) pretreatment for 7 d can irreversibly interrupt somatic embryo formation, whilst both reduced and oxidized forms of glutathione enhance root formation via a mechanism independent of ethylene perception, as determined by analysis of the ethylene-insensitive skl mutant. It was also shown that quercetin and the well-known auxin transport inhibitor NPA (N-1-naphthylphthalamic acid), which has a similar structure to quercetin, and isoflavonoids formononetin and genistein caused severe reduction in root formation. Also, the relative expression of several transcription factors was analysed in 1-week-old NAA-treated explants (stem cell niche formation stage), in NAA- and BAP-treated explants (no root formation), and in the roots of germinated seeds. The results showed, for the first time in a legume, that the transcription factors homeodomain WOX5 and the AP2-domain containing PLETHORA1 and 2, BABY BOOM1 were strongly induced by auxin addition, while cytokinin addition dramatically reduced their expression, indicating a role for these genes in the formation of root stem cell niches.