Subspecialization of R2R3-MYB Repressors for Anthocyanin and Proanthocyanidin Regulation in Forage Legumes.
Subspecialization of R2R3-MYB Repressors for Anthocyanin and Proanthocyanidin Regulation in Forage Legumes.
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DOI：
10.3389/fpls.2015.01165
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发表时间：
2015
影响因子：
5.6
通讯作者：
Albert NW
中科院分区：
文献类型：
--
作者：
Albert NW
迄今为止研究的所有被子植物中，花色素苷色素和原花色素（缩合单宁）的合成都受到MYB-bHLH-WDR（MBW）转录因子复合体的调节。Tr-MYB 133和Tr-MYB 134是从白车轴草中分离的，并且编码拮抗MBW活化复合物的活性的R2 R3-MYB。这两个基因在其他豆类物种中是保守的，并且在MYB阻遏物的较大花青素/原花青素进化枝内形成两个亚进化枝。然而，与矮牵牛和拟南芥不同，这些R2 R3-MYB阻遏物不能阻止花青素或原花青素的异位积累。相反，它们在花青素或原花青素合成时表达，并为MBW复合物提供反馈调节。这种反馈的发生是因为Tr-MYB 133和Tr-MYB 134本身受到MBW复合物的调节。Tr-MYB 133由含有花青素相关R2 R3-MYB蛋白的MBW复合物（Tr-RED LEAF）调节，而Tr-MYB 134由含有原花青素R2 R3-MYB的复合物（Tr-MYB 14）调节。MBW基因调控网络的其他特征在豆类中也是保守的，包括花青素MBW复合物激活AN 1/TT 8进化枝bHLH因子表达的能力。Tr-MYB 133和Tr-MYB 134通过不同的途径特异性MBW复合物的调节导致了控制花青素苷或原花青素合成的亚专业化。
The synthesis of anthocyanin pigments and proanthocyanidins (condensed tannins) is regulated by MYB-bHLH-WDR (MBW) transcription factor complexes in all angiosperms studied to date. Tr-MYB133 and Tr-MYB134 were isolated from Trifolium repens and encode R2R3-MYBs that antagonize the activity of MBW activation complexes. These two genes are conserved in other legume species, and form two sub-clades within the larger anthocyanin/proanthocyanidin clade of MYB repressors. However, unlike petunia and Arabidopsis, these R2R3-MYB repressors do not prevent ectopic accumulation of anthocyanins or proanthocyanidins. Instead, they are expressed when anthocyanins or proanthocyanidins are being synthesized, and provide feedback regulation to MBW complexes. This feedback occurs because Tr-MYB133 and Tr-MYB134 are themselves regulated by MBW complexes. Tr-MYB133 is regulated by MBW complexes containing anthocyanin-related R2R3-MYB proteins (Tr-RED LEAF), while Tr-MYB134 is regulated by complexes containing the proanthocyanidin R2R3-MYBs (Tr-MYB14). Other features of the MBW gene regulation networks are also conserved within legumes, including the ability for the anthocyanin MBW complexes to activate the expression of the AN1/TT8 clade bHLH factor. The regulation of Tr-MYB133 and Tr-MYB134 by distinct, pathway-specific MBW complexes has resulted in subspecialization for controlling anthocyanin or proanthocyanidin synthesis.