Subfunctionalization of Cellulose Synthases in Seed Coat Epidermal Cells Mediates Secondary Radial Wall Synthesis and Mucilage Attachment
Subfunctionalization of Cellulose Synthases in Seed Coat Epidermal Cells Mediates Secondary Radial Wall Synthesis and Mucilage Attachment
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DOI：
10.1104/pp.111.179069
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发表时间：
2011-09-01
期刊：
影响因子：
7.4
通讯作者：
DeBolt, Seth
中科院分区：
文献类型：
--
作者：
Mendu, Venugopal;Griffiths, Jonathan S.;DeBolt, Seth
拟南芥（Arabidopsis thaliana）表皮种皮细胞遵循一个复杂的发育程序，受精后，胚珠外珠被细胞分化成一个独特的细胞类型。这些细胞的两个特征是产生一个充满果胶粘液的甜甜圈状质外体口袋和一个厚的次生细胞壁--柱。纤维素被认为是这两种次生细胞壁过程的关键组分。在这里，我们研究了纤维素合成酶（CESA）亚基CESA 2，CESA 5和CESA 9在种皮表皮中的作用。我们的特点是这些CESA蛋白在种皮中的作用，通过分析细胞壁组成和形态在CESA突变株系。这三个基因中的任何一个突变都会导致纤维素含量降低，细胞形状均匀性丧失，径向壁完整性降低。此外，我们发现，附着的粘液晕的父母种子挤压后保持纤维素为基础的连接需要CESA 5。因此，我们表明，纤维素履行的细胞外粘液基质和亲本细胞在种皮表皮细胞之间的粘附作用。我们建议，粘液仍然附着在种皮通过种子粘液和纤维素成分之间的相互作用。我们的数据表明，CESA 2和CESA 9在径向壁加固，CESA 5一样，但CESA 5也在粘液生物合成功能。这些数据表明不同CESA亚基在一种细胞类型中的独特作用，并说明了纤维素生物合成在植物发育生物学中的复杂作用。
Arabidopsis (Arabidopsis thaliana) epidermal seed coat cells follow a complex developmental program where, following fertilization, cells of the ovule outer integument differentiate into a unique cell type. Two hallmarks of these cells are the production of a doughnut-shaped apoplastic pocket filled with pectinaceous mucilage and the columella, a thick secondary cell wall. Cellulose is thought to be a key component of both these secondary cell wall processes. Here, we investigated the role of cellulose synthase (CESA) subunits CESA2, CESA5, and CESA9 in the seed coat epidermis. We characterized the roles of these CESA proteins in the seed coat by analyzing cell wall composition and morphology in cesa mutant lines. Mutations in any one of these three genes resulted in lower cellulose content, a loss of cell shape uniformity, and reduced radial wall integrity. In addition, we found that attachment of the mucilage halo to the parent seed following extrusion is maintained by cellulose-based connections requiring CESA5. Hence, we show that cellulose fulfills an adhesion role between the extracellular mucilage matrix and the parent cell in seed coat epidermal cells. We propose that mucilage remains attached to the seed coat through interactions between components in the seed mucilage and cellulose. Our data suggest that CESA2 and CESA9 serve in radial wall reinforcement, as does CESA5, but CESA5 also functions in mucilage biosynthesis. These data suggest unique roles for different CESA subunits in one cell type and illustrate a complex role for cellulose biosynthesis in plant developmental biology.