Ye Z H, Varner J E
Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
Plant Physiol. 1993 Nov;103(3):805-13. doi: 10.1104/pp.103.3.805.
Tracheary element formation from isolated Zinnia leaf mesophyll cells is an excellent system for the dissection of patterned secondary cell wall thickening and lignification. We used mRNAs from cells cultured for 48 h in the induction medium to isolate differentially regulated genes. Thirteen unique cDNA clones were isolated using a subtractive hybridization method. These clones can be divided into three distinct groups according to their characteristic gene expression in different media. The first group includes those genes whose expression is induced in the basal medium without 1-naphthaleneacetic acid (NAA) and benzyladenine; this indicates that the expression of these genes is regulated by chemical and physical factors other than these hormones. Three of these clones, p48h-229, p48h-114, and p48h-102, show significant homology to a pathogenesis-related protein II, a serine proteinase inhibitor, and a sunflower anther-specific proline-rich protein, respectively. The second group includes those genes whose expression is mainly NAA induced. One of these clones, p48h-10, shows high protein sequence homology to a barley aleurone-specific cDNA, B11E. The p48h-10-encoded protein shares some common characteristics of plant nonspecific lipid transfer proteins (low molecular weight, the secretion signal peptide, eight conserved cysteine residues, and a basic protein), although no significant protein sequence homology is found between p48-10 and other plant nonspecific lipid transfer proteins. The third group includes those genes whose expression is induced primarily in the induction medium; this indicates that the expression of these genes is closely associated with the process of tracheary element formation. Two of these clones, p48h-107 and p48h-17, show high homology to adenylate kinase and papaya proteinase I, respectively. The possible roles of these differentiation-specific genes during tracheary element formation are discussed.
从百日草叶片叶肉细胞中诱导气管元件的形成是研究模式化次生细胞壁增厚和木质化的理想体系。我们使用在诱导培养基中培养48小时的细胞的mRNA来分离差异表达基因。通过消减杂交法分离出13个独特的cDNA克隆。根据这些克隆在不同培养基中的特征性基因表达，可将它们分为三个不同的组。第一组包括那些在不含1-萘乙酸（NAA）和苄基腺嘌呤的基础培养基中表达被诱导的基因；这表明这些基因的表达受这些激素以外的化学和物理因素调控。这些克隆中的三个，p48h - 229、p48h - 114和p48h - 102，分别与病程相关蛋白II、丝氨酸蛋白酶抑制剂和向日葵花药特异性富含脯氨酸蛋白具有显著同源性。第二组包括那些主要受NAA诱导表达的基因。其中一个克隆，p48h - 10，与大麦糊粉层特异性cDNA B11E具有高度的蛋白质序列同源性。p48h - 10编码的蛋白质具有植物非特异性脂质转移蛋白的一些共同特征（低分子量、分泌信号肽、八个保守的半胱氨酸残基和碱性蛋白），尽管在p48 - 10与其他植物非特异性脂质转移蛋白之间未发现显著的蛋白质序列同源性。第三组包括那些主要在诱导培养基中表达被诱导的基因；这表明这些基因的表达与气管元件的形成过程密切相关。这些克隆中的两个，p48h - 107和p48h - 17，分别与腺苷酸激酶和木瓜蛋白酶I具有高度同源性。本文还讨论了这些分化特异性基因在气管元件形成过程中的可能作用。
