Brassinosteroids regulate plant growth through distinct signaling pathways in Selaginella and Arabidopsis.
Brassinosteroids regulate plant growth through distinct signaling pathways in Selaginella and Arabidopsis.
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DOI：
10.1371/journal.pone.0081938
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Choe S
中科院分区：
文献类型：
--
作者：
Cheon J;Fujioka S;Dilkes BP;Choe S
油菜素类固醇 (BR) 是促进生长的类固醇激素，可调节植物的多种生理过程。大多数 BR 生物合成酶属于细胞色素 P450 (CYP) 家族。拟南芥中编码 BR 生物合成最终步骤的基因可能是通过基因复制进化而来的，随后以双子叶植物特有的方式进行功能特化。为了深入了解 BR 的进化，我们对祖先维管植物石松植物卷柏 (Selaginella moellendorffii) 中的拟南芥 BR 生物合成基因进行了基因组重建。卷柏包含 CYP90 家族的四个成员，它们聚集在 CYP85 家族中。与已知的 BR 生物合成基因类似，卷柏 CYP90 显示八个或十个外显子，并且卷柏产生假定的 BR 生物合成中间体。因此，我们推测卷柏CYP90基因编码BR生物合成酶。与拟南芥中的典型 CYP 相比，卷柏 CYP90E2 和 CYP90F1 不具有氨基末端信号肽，表明它们不定位于内质网。此外，CYP 酶功能所需的三种推定 CYP 还原酶 (CPR) 之一与 CYP90E2 和 CYP90F1 共定位。 BR生物合成抑制剂丙环唑和表油菜素内酯的治疗分别导致生长大大延迟和增加。这表明 BR 促进卷柏属的生长，就像它们在拟南芥中一样。然而，BR 信号传导通过与拟南芥不同的途径发生。卷柏中不存在与拟南芥BR受体BRI1同源的序列，但存在下游成分，包括BIN2、BSU1和BZR1。因此，卷柏中启动 BR 信号传导的机制似乎与拟南芥中的不同。我们的研究结果表明，BR 作为生长促进激素的基本生理作用在石松植物和拟南芥中都是保守的。然而，不同的 BR 分子和基于 BRI1 的膜受体复合物在这些植物中进化出来。
Brassinosteroids (BRs) are growth-promoting steroid hormones that regulate diverse physiological processes in plants. Most BR biosynthetic enzymes belong to the cytochrome P450 (CYP) family. The gene encoding the ultimate step of BR biosynthesis in Arabidopsis likely evolved by gene duplication followed by functional specialization in a dicotyledonous plant-specific manner. To gain insight into the evolution of BRs, we performed a genomic reconstitution of Arabidopsis BR biosynthetic genes in an ancestral vascular plant, the lycophyte Selaginella moellendorffii. Selaginella contains four members of the CYP90 family that cluster together in the CYP85 clan. Similar to known BR biosynthetic genes, the Selaginella CYP90s exhibit eight or ten exons and Selaginella produces a putative BR biosynthetic intermediate. Therefore, we hypothesized that Selaginella CYP90 genes encode BR biosynthetic enzymes. In contrast to typical CYPs in Arabidopsis, Selaginella CYP90E2 and CYP90F1 do not possess amino-terminal signal peptides, suggesting that they do not localize to the endoplasmic reticulum. In addition, one of the three putative CYP reductases (CPRs) that is required for CYP enzyme function co-localized with CYP90E2 and CYP90F1. Treatments with a BR biosynthetic inhibitor, propiconazole, and epi-brassinolide resulted in greatly retarded and increased growth, respectively. This suggests that BRs promote growth in Selaginella, as they do in Arabidopsis. However, BR signaling occurs through different pathways than in Arabidopsis. A sequence homologous to the Arabidopsis BR receptor BRI1 was absent in Selaginella, but downstream components, including BIN2, BSU1, and BZR1, were present. Thus, the mechanism that initiates BR signaling in Selaginella seems to differ from that in Arabidopsis. Our findings suggest that the basic physiological roles of BRs as growth-promoting hormones are conserved in both lycophytes and Arabidopsis; however, different BR molecules and BRI1-based membrane receptor complexes evolved in these plants.
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