Expression of the R2R3-MYB Transcription Factor TaMYB14 from Trifolium arvense Activates Proanthocyanidin Biosynthesis in the Legumes Trifolium repens and Medicago sativa
Expression of the R2R3-MYB Transcription Factor TaMYB14 from Trifolium arvense Activates Proanthocyanidin Biosynthesis in the Legumes Trifolium repens and Medicago sativa
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DOI：
10.1104/pp.112.195420
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发表时间：
2012-07-01
期刊：
影响因子：
7.4
通讯作者：
Rasmussen, Susanne
中科院分区：
文献类型：
--
作者：
Hancock, Kerry R.;Collette, Vern;Rasmussen, Susanne
原花青素(PAS)是一类低聚黄酮类化合物，是苯丙烷途径的一组终产物。据报道，腐植酸有益于人和动物的健康，在畜牧农业系统中特别重要，可以改善动物生产和减少温室气体排放。然而，在这些系统中种植的主要饲用豆类植物，如白三叶和紫花苜蓿，在叶子中不含有任何大量的多胺。我们从富含PA的豆科植物白三叶的叶片中鉴定出一个R2R3-MYB转录因子TaMYB14，并为该转录因子参与豆科植物PA生物合成的调控提供了证据。TaMYB14的表达是上调苯丙烷途径后期步骤和诱导PA生物合成的必要条件和充分条件。TaMYB14的RNA干扰沉默导致Arvense几乎完全停止PA的生物合成，而表达TaMYB14的烟草、M.sativa和T.reppens植株合成并积累了高达1.8%干物质的PAS。靶向高效液相色谱-多级串联质谱仪分析表明，叶片提取物中的PAS聚合度高达6。因此，表达TaMYB14的转基因紫花苜蓿和紫花苜蓿为改善动物健康和减轻畜牧生产系统对环境的负面影响提供了一个可行的选择。
Proanthocyanidins (PAs) are oligomeric flavonoids and one group of end products of the phenylpropanoid pathway. PAs have been reported to be beneficial for human and animal health and are particularly important in pastoral agricultural systems for improved animal production and reduced greenhouse gas emissions. However, the main forage legumes grown in these systems, such as Trifolium repens and Medicago sativa, do not contain any substantial amounts of PAs in leaves. We have identified from the foliar PA-accumulating legume Trifolium arvense an R2R3-MYB transcription factor, TaMYB14, and provide evidence that this transcription factor is involved in the regulation of PA biosynthesis in legumes. TaMYB14 expression is necessary and sufficient to up-regulate late steps of the phenylpropanoid pathway and to induce PA biosynthesis. RNA interference silencing of TaMYB14 resulted in almost complete cessation of PA biosynthesis in T. arvense, whereas Nicotiana tabacum, M. sativa, and T. repens plants constitutively expressing TaMYB14 synthesized and accumulated PAs in leaves up to 1.8% dry matter. Targeted liquid chromatography-multistage tandem mass spectrometry analysis identified foliar PAs up to degree of polymerization 6 in leaf extracts. Hence, genetically modified M. sativa and T. repens plants expressing TaMYB14 provide a viable option for improving animal health and mitigating the negative environmental impacts of pastoral animal production systems.