Department of Wood Science, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Biotechnology Platform, Agricultural Research Council, Onderstepoort, Pretoria 0110, South Africa.
Plant Cell. 2017 Aug;29(8):2000-2015. doi: 10.1105/tpc.17.00338. Epub 2017 Jul 20.
Alkenes are linear hydrocarbons with one or more double bonds. Despite their potential as biofuels and precursors for specialty chemicals, the underlying biochemistry and genetics of alkene biosynthesis in plants remain elusive. Here, we report on a screen of natural accessions of poplar (), revealing that the leaf cuticular waxes are predominantly composed of alkanes and alkenes. Interestingly, the accumulation of alkenes increases with leaf development, is limited to the abaxial side of the leaf, and is impaired in a few accessions. Among other genes, a β-ketoacyl CoA synthase gene () was downregulated in leaves from non-alkene-producing accessions. We demonstrated biochemically that PotriKCS1 elongates monounsaturated fatty acids and is responsible for the recruitment of unsaturated substrates to the cuticular wax. Moreover, we found significant associations between the presence of alkenes and tree growth and resistance to leaf spot. These findings highlight the crucial role of cuticular waxes as the first point of contact with the environment, and they provide a foundation for engineering long-chain monounsaturated oils in other species.
烯烃是具有一个或多个双键的线性碳氢化合物。尽管它们有可能成为生物燃料和特种化学品的前体，但植物中烯烃生物合成的基础生物化学和遗传学仍然难以捉摸。在这里，我们报告了杨树（）天然品系的筛选结果，表明叶角质层蜡主要由烷烃和烯烃组成。有趣的是，烯烃的积累随着叶片的发育而增加，仅限于叶片的背面，并且在少数品系中受到损害。在其他基因中，一种β-酮酰基辅酶 A 合酶基因（）在非烯烃产生品系的叶片中下调。我们通过生物化学证明，PotriKCS1 延长了单不饱和脂肪酸，并负责将不饱和底物招募到角质层蜡中。此外，我们发现烯烃的存在与树木生长和对叶斑病的抗性之间存在显著关联。这些发现强调了角质层蜡作为与环境接触的第一点的关键作用，并为在其他物种中工程长链单不饱和油提供了基础。
