Tung Chih-Wei, Dwyer Kathleen G, Nasrallah Mikhail E, Nasrallah June B
Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA.
Plant Physiol. 2005 Jun;138(2):977-89. doi: 10.1104/pp.105.060558. Epub 2005 May 13.
Plant reproductive development is dependent on successful pollen-pistil interactions. In crucifers, the pollen tube must breach the stigma surface and burrow through the extracellular matrix of the stigma epidermal cells and transmitting tract cells before reaching its ovule targets. The high degree of specificity in pollen-pistil interactions and the precision of directional pollen tube growth suggest that signals are continually being exchanged between pollen/pollen tubes and cells of the pistil that line their path. However, with few exceptions, little is known about the genes that control these interactions. The specialized functions of stigma epidermal cells and transmitting tract cells are likely to depend on the activity of genes expressed specifically in these cells. In order to identify these genes, we used the Arabidopsis (Arabidopsis thaliana) ATH1 microarray to compare the whole-genome transcriptional profiles of stigmas and ovaries isolated from wild-type Arabidopsis and from transgenic plants in which cells of the stigma epidermis and transmitting tract were specifically ablated by expression of a cellular toxin. Among the 23,000 genes represented on the array, we identified 115 and 34 genes predicted to be expressed specifically in the stigma epidermis and transmitting tract, respectively. Both gene sets were significantly enriched in predicted secreted proteins, including potential signaling components and proteins that might contribute to reinforcing, modifying, or remodeling the structure of the extracellular matrix during pollination. The possible role of these genes in compatible and incompatible pollen-pistil interactions is discussed.
植物的生殖发育依赖于花粉与雌蕊之间成功的相互作用。在十字花科植物中,花粉管必须穿透柱头表面,并在到达胚珠目标之前,在柱头表皮细胞和传递组织细胞的细胞外基质中穿行。花粉与雌蕊相互作用的高度特异性以及花粉管定向生长的精确性表明,花粉/花粉管与沿其路径排列的雌蕊细胞之间不断地进行着信号交换。然而,除了少数例外,对于控制这些相互作用的基因知之甚少。柱头表皮细胞和传递组织细胞的特殊功能可能取决于这些细胞中特异性表达的基因的活性。为了鉴定这些基因,我们使用拟南芥ATH1基因芯片,比较了从野生型拟南芥以及通过表达细胞毒素特异性消融柱头表皮细胞和传递组织细胞的转基因植物中分离出的柱头和子房的全基因组转录谱。在芯片上所代表的23000个基因中,我们分别鉴定出115个和34个预计在柱头表皮和传递组织中特异性表达的基因。这两组基因在预测的分泌蛋白中均显著富集,包括潜在的信号成分以及可能在授粉过程中有助于强化、修饰或重塑细胞外基质结构的蛋白质。本文讨论了这些基因在亲和与不亲和花粉 - 雌蕊相互作用中的可能作用。