Functional Analyses of an Epicuticular Wax Gene from Arabidopsis

9419093费尔德曼所有植物的角质层表面都含有表皮层蜡(EW)。扫描电子显微镜显示，在许多植物物种中，电子战由无定形的基层组成，覆盖着杆状结构和边缘圆形的不规则形状的板状结构。这种蜡是由长链脂肪族化合物的混合物组成的，可以通过将植物的地上部分浸泡在氯仿或己烷中几秒钟，然后蒸发溶剂来分离。脂肪族化合物包括烷烃、酯、β-二酮、醛、伯醇和仲醇、酮、游离酸和三萜类。植物物种之间存在着巨大的多样性，无论是在蜡中存在的化学类别的数量上，还是在它们的相对丰富度上。即使在单个植物中，多毛的器官也可以通过EW组成的数量和质量上的差异来表征。对蜡的生化途径知之甚少，对这些分子如何通过细胞壁和角质层出口到表面的了解更少。然而，在拟南芥中分离到了大量的EW突变体，这使得研究者可以采取遗传和分子的方法来解剖表皮层蜡质通路。这项提议的目标是克隆和鉴定其中的两个基因，CER4和CER21。CER4基因的突变消除了伯醇的积累，而CER21基因的突变几乎消除了所有的醛。这两个基因都将被测序。它们在叶、茎和角果中的表达水平将在发育过程中表征。此外，还将研究CER4和CER21基因在几种环境条件下生长的植物中的表达。这两个基因的细胞类型特异性表达将被研究。亚细胞定位将通过使用针对CER4和CER21蛋白的抗体进行原位分析来进行。S还研究了这些基因在植物中的功能，即它们在生物合成、运输或调节中是否重要。有大量证据表明，EW的组成在食草性昆虫选择寄主植物时是重要的。通过基因工程方法改造电子战应该使我们能够在一些重要的农艺作物中提供对各种害虫的抗性。通过对拟南芥的修饰，可用于农艺植物蜡质的修饰。

9419093 Feldmann All plants contain epicuticular wax (EW) on the surface of the cuticle. Scanning electron microscopy has revealed that in many plant species the EW consists of an amorphous ground layer covered by rod-shaped structures and irregular shaped plate-like structures with rounded edges. The wax is composed of a mixture of long chain aliphatic compounds which can be isolated by dipping an aerial portion of the plant into chloroform or hexane for a few seconds and then evaporating the solvent. The aliphatic compounds include alkanes, esters, beta-diketones, aldehydes, primary and secondary alcohols, ketones, free acids, and triterpenes. There is tremendous diversity among plant species both in the number of chemical classes present in a wax and in their relative abundance. Even within an individual plant the vairous organs can be characterized by quantitative and qualitative differences in the EW composition. The wax biochemical pathway is poorly understood and even less is known about the export of these molecules through the cell wall and cuticle to the surface. However, a large number of EW mutants have been isolated in Arabidopsis, which allows the investigator to take a genetic and molecular approach to dissecting the epicuticular wax pathway. The objective of this proposal is to clone and characterize two of these genes, CER4 and CER21. The mutation at the CER4 locus eliminates the accumulation of primary alcohols whicle a mutation at the CER21 locus eliminates nearly all of the aldehydes. Both genes will be sequenced. Their expression level in leaves, stems and siliques will be characterized during development. Also, the expression of the CER4 and CER21 genes will be studied in plants grown under several encironmental regimes. The cell-type specific expression of these two genes will be studied. Subcellular localization will be performed via in situ analyses with antibodies raised against the CER4 and CER21 proteins. Also s tudied will be the function of these genes in the plant, i.e., are they important in biosynthesis, transport, or regulation. There is substantial evidence to show that the composition of the EW is important in host plant selection by herbivorous insects. Modification of the EW via genetic engineering methods should enable us to provide resistance to various insect pests in a number of important agronomic crops. The results obtained from the modification of Arabidopsis can be used to modify the waxes on agronomic plants.