Horn Patrick J, Liu Jinjie, Cocuron Jean-Christophe, McGlew Kathleen, Thrower Nicholas A, Larson Matt, Lu Chaofu, Alonso Ana P, Ohlrogge John
Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA.
Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA.
Plant J. 2016 May;86(4):322-48. doi: 10.1111/tpj.13163.
Two Brassicaceae species, Physaria fendleri and Camelina sativa, are genetically very closely related to each other and to Arabidopsis thaliana. Physaria fendleri seeds contain over 50% hydroxy fatty acids (HFAs), while Camelina sativa and Arabidopsis do not accumulate HFAs. To better understand how plants evolved new biochemical pathways with the capacity to accumulate high levels of unusual fatty acids, transcript expression and protein sequences of developing seeds of Physaria fendleri, wild-type Camelina sativa, and Camelina sativa expressing a castor bean (Ricinus communis) hydroxylase were analyzed. A number of potential evolutionary adaptations within lipid metabolism that probably enhance HFA production and accumulation in Physaria fendleri, and, in their absence, limit accumulation in transgenic tissues were revealed. These adaptations occurred in at least 20 genes within several lipid pathways from the onset of fatty acid synthesis and its regulation to the assembly of triacylglycerols. Lipid genes of Physaria fendleri appear to have co-evolved through modulation of transcriptional abundances and alterations within protein sequences. Only a handful of genes showed evidence for sequence adaptation through gene duplication. Collectively, these evolutionary changes probably occurred to minimize deleterious effects of high HFA amounts and/or to enhance accumulation for physiological advantage. These results shed light on the evolution of pathways for novel fatty acid production in seeds, help explain some of the current limitations to accumulation of HFAs in transgenic plants, and may provide improved strategies for future engineering of their production.
两种十字花科植物，芬德勒氏膀胱果（Physaria fendleri）和亚麻荠（Camelina sativa），在基因上与拟南芥（Arabidopsis thaliana）彼此密切相关。芬德勒氏膀胱果种子含有超过50%的羟基脂肪酸（HFAs），而亚麻荠和拟南芥不会积累HFAs。为了更好地理解植物如何进化出能够积累高水平异常脂肪酸的新生化途径，对芬德勒氏膀胱果、野生型亚麻荠以及表达蓖麻（Ricinus communis）羟化酶的亚麻荠发育种子的转录表达和蛋白质序列进行了分析。揭示了脂质代谢中一些潜在的进化适应性变化，这些变化可能增强了芬德勒氏膀胱果中HFA的产生和积累，而在缺乏这些变化的情况下，则限制了转基因组织中的积累。这些适应性变化发生在从脂肪酸合成及其调控到三酰甘油组装的几个脂质途径中的至少20个基因中。芬德勒氏膀胱果的脂质基因似乎通过转录丰度的调节和蛋白质序列的改变而共同进化。只有少数基因显示出通过基因复制进行序列适应的证据。总的来说，这些进化变化可能是为了将高HFA含量的有害影响降至最低和/或为了生理优势而增强积累。这些结果揭示了种子中新型脂肪酸产生途径的进化，有助于解释目前转基因植物中HFA积累的一些限制，并可能为其未来生产工程提供改进策略。
