SummaryVery‐long‐chain (VLC) alkanes are major components of hydrophobic cuticular waxes that cover the aerial epidermis of land plants, serving as a waterproofing barrier to protect the plant against environmental stresses. The mechanism of VLC‐alkane biosynthesis has been extensively elucidated in plants. However, little is known about the biosynthesis of long‐chain alkanes (LC, C13 ~ C19) such as pentadecane in plants. Alkanes with different chain lengths are also major constituents of fossil fuels and thus the discovery of the alkane biosynthetic machinery in plants would provide a toolbox of enzymes for the production of renewable hydrocarbon sources and next generations of biofuels. The top leaves of Pogostemon cablin at young stage accumulate large amounts of LC‐alkane pentadecane, making this plant an excellent system for the elucidation of LC‐alkane biosynthetic machinery in plant. We show here that LC‐alkane pentadecane biosynthesis in P. cablin involves an endoplasmic reticulum (ER)‐localized complex made of PcCER1‐LIKE3 and PcCER3, homologues of Arabidopsis ECERIFERUM1 (AtCER1) and AtCER3 proteins that are involved in Arabidopsis VLC‐alkane biosynthesis. We reconstitute the biosynthesis of pentadecane in Nicotiana benthamiana by co‐expression of PcCER1‐LIKE3 and PcCER3 and further improve its production by silencing multifunctional acetyl‐CoA carboxylases involved in fatty acid elongation pathway. Taken together, we uncovered the key biosynthetic machinery of LC‐alkane pentadecane in P. cablin and demonstrated that using these newly identified enzymes to engineer this LC‐alkane for liquid biofuel production in a heterologous plant host is possible.

中文翻译：

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Pogostemon cablin 长链烷烃十五烷生物合成的途径阐明和异源重构


摘要超长链 （VLC） 烷烃是覆盖在陆地植物气层表皮上的疏水性表皮蜡的主要成分，可作为防水屏障，保护植物免受环境压力。VLC-烷烃生物合成的机制已在植物中得到广泛阐明。然而，人们对植物中十五烷等长链烷烃 （LC， C13 ~ C19） 的生物合成知之甚少。具有不同链长的烷烃也是化石燃料的主要成分，因此在植物中发现烷烃生物合成机制将为生产可再生碳氢化合物来源和下一代生物燃料提供酶工具箱。Pogostemon cablin 在幼苗期的顶叶积累了大量的 LC-烷烃十五烷，使该植物成为阐明植物中 LC-烷烃生物合成机制的极好系统。我们在这里表明，P. cablin 中的 LC-烷烃五十烷生物合成涉及由 PcCER1-LIKE3 和 PcCER3 组成的内质网 （ER） 定位复合物，拟南芥 ECERIFERUM1 （AtCER1） 和 AtCER3 蛋白的同源物参与拟南芥 VLC-烷烃生物合成。我们通过共表达 PcCER1-LIKE3 和 PcCER3 重建本氏烟草中十五烷的生物合成，并通过沉默参与脂肪酸延伸途径的多功能乙酰辅酶 A 羧化酶进一步提高其生产。综上所述，我们发现了 P. cablin 中 LC-烷烃十五烷的关键生物合成机制，并证明使用这些新发现的酶来设计这种 LC-烷烃，以便在异源植物宿主中生产液体生物燃料是可能的。