Cheung A Y, May B, Kawata E E, Gu Q, Wu H M
Department of Biology, Yale University, New Haven, CT 06511.
Plant J. 1993 Jan;3(1):151-60.
The pistil of flowers is a specialized organ which contains the female gametophytes and provides the structures necessary for pollination and fertilization. Pollen deposited on the stigmatic surface of a compatible plant germinates a pollen tube which penetrates the stigmatic papillae and grows intercellularly through the style towards the ovules in the ovary. Pollen tube growth is largely restricted to the transmitting tissue in the style. Therefore the stylar transmitting tissue is extremely important for the migration of the pollen cell towards the ovary. We have isolated two related cDNAs, transmitting tissue-specific (TTS)-1 and TTS-2, derived from two proline-rich protein (PRP)-encoding mRNAs that accumulate specifically in the transmitting tissue of tobacco. The deduced PRP sequences share similarities with proline-rich cell wall glycoproteins found in a variety of plants. TTS-1 and TTS-2 mRNAs are induced in very young floral buds, accumulate most abundantly during the later stages of flower development when style elongation is the most rapid, and remain at relatively high levels at anthesis. These mRNAs become undetectable in maturing green fruits. In situ hybridization shows that TTS-1 and TTS-2 mRNA accumulation is restricted to the transmitting tissue of the style. The possible roles that these transmitting tissue-specific PRPs may play in maintaining the structural integrity of the style or in the function of this organ is discussed.
花的雌蕊是一个特殊的器官，它包含雌配子体，并提供授粉和受精所需的结构。落在亲和植物柱头上的花粉萌发出花粉管，花粉管穿透柱头乳突，并通过花柱在细胞间向子房中的胚珠生长。花粉管的生长在很大程度上局限于花柱中的传递组织。因此，花柱传递组织对于花粉细胞向子房的迁移极为重要。我们从两个富含脯氨酸的蛋白（PRP）编码的mRNA中分离出两个相关的cDNA，即传递组织特异性（TTS）-1和TTS-2，它们在烟草的传递组织中特异性积累。推导的PRP序列与在多种植物中发现的富含脯氨酸的细胞壁糖蛋白具有相似性。TTS-1和TTS-2 mRNA在非常幼嫩的花芽中被诱导，在花发育后期花柱伸长最快时积累最为丰富，并且在开花期保持相对较高的水平。这些mRNA在成熟的绿色果实中无法检测到。原位杂交表明，TTS-1和TTS-2 mRNA的积累局限于花柱的传递组织。本文讨论了这些传递组织特异性PRP在维持花柱结构完整性或该器官功能中可能发挥的作用。
