Institute of Biology Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
J Exp Bot. 2022 May 13;73(9):2875-2888. doi: 10.1093/jxb/erab533.
A central goal of green chemistry is to produce industrially useful fatty acids in oilseed crops. Although genes encoding suitable fatty acid-modifying enzymes are available from more than a dozen wild species, progress has been limited because expression of these enzymes in transgenic plants produces only low yields of the desired products. For example, fatty acid hydroxylase 12 (FAH12) from castor (Ricinus communis) produces only 17% hydroxy fatty acids (HFAs) when expressed in Arabidopsis (Arabidopsis thaliana), compared with 90% HFAs in castor seeds. The transgenic plants also have reduced oil content and seed vigor. Here, we review experiments that have provided for steady increased HFA accumulation and oil content. This research has led to exciting new discoveries of enzymes and regulatory processes in the pathways of both seed oil synthesis and lipid metabolism in other parts of the plant. Recent investigations have revealed that HFA-accumulating seeds are unable to rapidly mobilize HFA-containing triacylglycerol (TAG) storage lipid after germination to provide carbon and energy for seedling development, resulting in reduced seedling establishment. These findings present a new opportunity to investigate a different, key area of lipid metabolism-the pathways of TAG lipolysis and β-oxidation in germinating seedlings.
绿色化学的一个核心目标是在油料作物中生产具有工业用途的脂肪酸。尽管有十几种野生物种的基因编码适合的脂肪酸修饰酶，但进展有限，因为这些酶在转基因植物中的表达仅产生所需产物的低产量。例如，蓖麻（Ricinus communis）的脂肪酸羟化酶 12（FAH12）在拟南芥（Arabidopsis thaliana）中表达时仅产生 17%的羟基脂肪酸（HFAs），而在蓖麻种子中则产生 90%的 HFAs。转基因植物的油含量和种子活力也降低了。在这里，我们回顾了那些为稳定增加 HFA 积累和油含量提供实验的研究。这项研究导致了在种子油合成和植物其他部位脂质代谢途径中酶和调节过程的令人兴奋的新发现。最近的调查显示，积累 HFA 的种子在萌发后无法快速动员含 HFA 的三酰基甘油（TAG）储存脂质，为幼苗发育提供碳和能量，从而导致幼苗定植减少。这些发现为研究脂质代谢的一个不同的关键领域——萌发幼苗中 TAG 水解和β-氧化途径提供了一个新的机会。
