Li Runzhi, Yu Keshun, Hildebrand David F
Department of Plant and Soil Science, University of Kentucky, Lexington, KY 40546, USA.
Lipids. 2010 Feb;45(2):145-57. doi: 10.1007/s11745-010-3385-4. Epub 2010 Jan 27.
Triacylglycerol (TAG) is the main storage lipid in plants. Acyl-CoA: diacylglycerol acyltransferase (DGAT1 and DGAT2) and phospholipid: diacylglycerol acyltransferase (PDAT) can catalyze TAG synthesis. It is unclear how these three independent genes are regulated in developing seeds, and particularly if they have specific functions in the high accumulation of unusual fatty acids in seed oil. The expression patterns of DGAT1, DGAT2 and a PDAT in relation to the accumulation of oil and epoxy and hydroxy fatty acids in developing seeds of the plant species Vernonia galamensis, Euphorbia lagascae, Stokesia laevis and castor that accumulate high levels of these fatty acids in comparison with soybean and Arabidopsis were investigated. The expression patterns of DGAT1, DGAT2 and the PDAT are consistent with all three enzymes playing a role in the high epoxy or hydroxy fatty acid accumulation in developing seeds of these plants. PDAT and DGAT2 transcript levels are present at much higher levels in developing seeds of epoxy and hydroxy fatty acid accumulating plants than in soybeans or Arabidopsis. Moreover, PDAT, DGAT1 and DGAT2 are found to be expressed in many different plant tissues, suggesting that these enzymes may have other roles in addition to seed oil accumulation. DGAT1 appears to be a major enzyme for seed oil accumulation at least in Arabidopsis and soybeans. For the epoxy and hydroxy fatty acid accumulating plants, DGAT2 and PDAT also show expression patterns consistent with a role in the selective accumulation of these unusual fatty acids in seed oil.
三酰甘油（TAG）是植物中的主要储存脂质。酰基辅酶A：二酰甘油酰基转移酶（DGAT1和DGAT2）以及磷脂：二酰甘油酰基转移酶（PDAT）可催化TAG的合成。目前尚不清楚这三个独立基因在发育中的种子中是如何被调控的，尤其是它们在种子油中异常脂肪酸的高积累过程中是否具有特定功能。研究了与大豆和拟南芥相比，在种子中积累高水平油、环氧脂肪酸和羟基脂肪酸的植物物种加拉曼非油菊、拉氏大戟、平滑匙叶草和蓖麻发育种子中DGAT1、DGAT2和一种PDAT的表达模式与油、环氧脂肪酸和羟基脂肪酸积累的关系。DGAT1、DGAT2和PDAT的表达模式表明，这三种酶在这些植物发育种子中环氧或羟基脂肪酸的高积累过程中均发挥作用。在积累环氧脂肪酸和羟基脂肪酸植物的发育种子中，PDAT和DGAT2的转录水平远高于大豆或拟南芥。此外，发现PDAT、DGAT1和DGAT2在许多不同的植物组织中均有表达，这表明这些酶除了在种子油积累中发挥作用外，可能还具有其他功能。至少在拟南芥和大豆中，DGAT1似乎是种子油积累的主要酶。对于积累环氧脂肪酸和羟基脂肪酸的植物，DGAT2和PDAT的表达模式也表明它们在种子油中这些异常脂肪酸的选择性积累过程中发挥作用。
