小背景：The expanding maize adult leaf displays a dynamic, proximodistal gradient of cuticle development, from the leaf base to the tip. 

研究手段：Laser microdissection RNA Sequencing (LM-RNAseq) was performed along this proximodistal gradient, and complementary network analyses identified potential regulators of cuticle biosynthesis and deposition.

分析+试验：A weighted gene coexpression network (WGCN) analysis suggested a previously undescribed function for PHYTOCHROME-mediated light signaling during the regulation of cuticular wax deposition. Genetic analyses reveal that phyB1 phyB2 double mutants of maize exhibit abnormal cuticle composition, supporting the predictions of our coexpression analysis. Reverse genetic analyses also show that phy mutants of the moss Physcomitrella patens exhibit abnormal cuticle composition, suggesting an ancestral role for PHYTOCHROME-mediated, light-stimulated regulation of cuticle development during plant evolution

 摘  要 

植物角质层（cuticle）由蜡与角质构成，在陆地植物中主要作为疏水性屏障，能够减少植物表皮的水分丢失。正在扩张中的玉米成年叶片角质层的发育从叶基到叶尖呈现出由近及远的动态梯度。作者沿着玉米叶片由近及远的梯度进行了激光显微切割转录组测序（LM-RNAseq），并通过互补网络分析鉴定了角质层合成与沉积的潜在调控因子。加权基因共表达网络分析（WGCNA）显示PHYTOCHROME介导的光信号在角质层蜡沉积调控中存在一个先前从未发现的功能。遗传分析显示phyB1 phyB2双突的玉米植株存在异常的角质层组成，验证了共表达分析的预测。反向遗传学分析显示苔藓植物小立碗藓的phy突变体存在异常的角质层组成，说明在植物演化过程中，由PHYTOCHROME介导的、光刺激角质层发育调控是一个比较古老的功能。

Plant cuticles provide barriers to water loss and arose as aquatic plants adapted to the dry terrestrial environment. The cuticle components, waxes and the fatty acid-based polymer cutin, are synthesized in the plant epidermis, exported across the cell wall, and deposited on the plant surface. This study suggests a role for PHYTOCHROME light receptors during cuticle development in leaves of maize and moss, diverse species that are separated by more than 400 million y of land plant evolution. We hypothesize that phytochrome-mediated light signaling contributed to the evolution of cuticles in land plants.

植物角质层为植物提供了最外层的屏障，减少水分丢失，伴随着水生植物适应干旱陆地环境而出现。角质层的组成，即蜡和基于脂肪酸多聚物的角质在植物的表皮合成，并且被转运到细胞壁之外，最终在植物的体表沉积，形成角质层。本文的研究显示PHYTOCHROME光受体在玉米和苔藓的角质层发育过程中发挥作用，而玉米与苔藓是两个在植物系统演化上分化超过四亿年的陆地植物物种。因此，作者认为由植物色素介导的光信号作用于陆地植物角质层的演化。

 通讯作者 

Michael J. Scanlon

个人简介：