Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA.
Proc Natl Acad Sci U S A. 2012 Jan 31;109(5):1766-71. doi: 10.1073/pnas.1120916109. Epub 2012 Jan 17.
MtPAR (Medicago truncatula proanthocyanidin regulator) is an MYB family transcription factor that functions as a key regulator of proanthocyanidin (PA) biosynthesis in the model legume Medicago truncatula. MtPAR expression is confined to the seed coat, the site of PA accumulation. Loss-of-function par mutants contained substantially less PA in the seed coat than the wild type, whereas levels of anthocyanin and other specialized metabolites were normal in the mutants. In contrast, massive accumulation of PAs occurred when MtPAR was expressed ectopically in transformed hairy roots of Medicago. Transcriptome analysis of par mutants and MtPAR-expressing hairy roots, coupled with yeast one-hybrid analysis, revealed that MtPAR positively regulates genes encoding enzymes of the flavonoid-PA pathway via a probable activation of WD40-1. Expression of MtPAR in the forage legume alfalfa (Medicago sativa) resulted in detectable levels of PA in shoots, highlighting the potential of this gene for biotechnological strategies to increase PAs in forage legumes for reduction of pasture bloat in ruminant animals.
MtPAR（紫花苜蓿原花青素调节因子）是一个 MYB 家族转录因子，作为模式豆科植物紫花苜蓿中原花青素（PA）生物合成的关键调节因子发挥作用。MtPAR 的表达仅限于种皮，即 PA 积累的部位。与野生型相比，功能丧失的 par 突变体种皮中的 PA 含量明显减少，而突变体中花青素和其他特殊代谢物的水平正常。相比之下，当 MtPAR 在转化的紫花苜蓿毛状根中异位表达时，大量的 PA 积累发生。par 突变体和 MtPAR 表达的毛状根的转录组分析，加上酵母单杂交分析，表明 MtPAR 通过 WD40-1 的可能激活正向调节类黄酮-PA 途径的基因编码酶。MtPAR 在饲料豆科植物紫花苜蓿中的表达导致在地上部分检测到 PA 的水平，突出了该基因在生物技术策略中的潜力，以增加饲料豆科植物中的 PA，从而减少反刍动物牧场膨气。
