The hydrophobic cuticle is the first line of defense between aerial portions of plants and the external environment. On maize (Zea mays L.) silks, the cuticular cutin matrix is infused with cuticular waxes, consisting of a homologous series of very long-chain fatty acids (VLCFAs), aldehydes, and hydrocarbons. Together with VLC fatty-acyl-CoAs (VLCFA-CoAs), these metabolites serve as precursors, intermediates and end-products of the cuticular wax biosynthetic pathway. To deconvolute the potentially confounding impacts of the change in silk microenvironment and silk development on this pathway, we profiled cuticular waxes on the silks of the inbreds B73 and Mo17, and their reciprocal hybrids. Multivariate interrogation of these metabolite abundance data demonstrates that VLCFA-CoAs and total free VLCFAs are positively correlated with the cuticular wax metabolome, and this metabolome is primarily affected by changes in the silk microenvironment and plant genotype. Moreover, the genotype effect on the pathway explains the increased accumulation of cuticular hydrocarbons with a concomitant reduction in cuticular VLCFA accumulation on B73 silks, suggesting that the conversion of VLCFA-CoAs to hydrocarbons is more effective in B73 than Mo17. Statistical modeling of the ratios between cuticular hydrocarbons and cuticular VLCFAs reveals a significant role of precursor chain length in determining this ratio. This study establishes the complexity of the product–precursor relationships within the silk cuticular wax-producing network by dissecting both the impact of genotype and the allocation of VLCFA-CoA precursors to different biological processes, and demonstrates that longer chain VLCFA-CoAs are preferentially utilized for hydrocarbon biosynthesis.

中文翻译：

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玉米丝角质层蜡烃和脂肪酸生成途径之间的动态关系

疏水性角质层是植物地上部分与外部环境之间的第一道防线。在玉米 (Zea mays L.) 丝上，角质层角质基质中注入了角质层蜡，由一系列同源的极长链脂肪酸 (VLCFA)、醛和碳氢化合物组成。这些代谢物与 VLC 脂肪酰基辅酶 As (VLCFA-CoAs) 一起充当角质蜡生物合成途径的前体、中间体和最终产物。为了消除丝微环境和丝发育的变化对该途径的潜在混杂影响，我们对自交系 B73 和 Mo17 及其互交杂种的丝上的角质层蜡进行了分析。对这些代谢物丰度数据的多变量询问表明，VLCFA-CoAs 和总游离 VLCFA 与角质层蜡代谢组呈正相关，并且该代谢组主要受蚕丝微环境和植物基因型变化的影响。此外，该途径的基因型效应解释了 B73 丝上角质层碳氢化合物积累的增加以及随之而来的角质层 VLCFA 积累的减少，这表明 VLCFA-CoAs 向碳氢化合物的转化在 B73 中比 Mo17 更有效。角质层碳氢化合物和角质层 VLCFA 之间比率的统计模型揭示了前体链长度在确定该比率方面的重要作用。本研究通过剖析基因型的影响和 VLCFA-CoA 前体在不同生物过程中的分配，确定了丝角质层产蜡网络中产物与前体关系的复杂性，并证明优先利用较长链的 VLCFA-CoA用于碳氢化合物生物合成。