Gu Q, Kawata E E, Morse M J, Wu H M, Cheung A Y
Department of Biology, Yale University, New Haven, CT 06511.
Mol Gen Genet. 1992 Jul;234(1):89-96. doi: 10.1007/BF00272349.
We isolated a flower-specific cDNA, FST (flower-specific thionin), which encodes a novel thionin from tobacco. Thionins are basic and cysteine (Cys)-rich, low molecular weight proteins found in many plants. They are believed to play a role in plant defense against pathogens. The central domain of the FST protein shares homology with three gamma-thionins. Like other thionin precursors, the FST protein has an N-terminal domain characteristic of a signal peptide and an acidic C-terminal domain. FST mRNA accumulates specifically in developing flowers and its level drops as flowers mature. Transcripts are present in petals, stamens and pistil but are not detectable in sepals. In situ hybridization revealed that FST mRNA is most abundant in the epidermal cells along the adaxial surface of petals, and in the surface cell layers of the carpel and anther walls. If the FST protein indeed has a protective role in flowers, this pattern of spatial distribution of FST mRNA would appear to maximize this effect on the two internal reproductive whorls. A possible biological role for FST is discussed.
我们分离出了一个花特异性的 cDNA，即 FST（花特异性硫堇蛋白），它编码一种来自烟草的新型硫堇蛋白。硫堇蛋白是一类碱性且富含半胱氨酸（Cys）的低分子量蛋白质，存在于许多植物中。人们认为它们在植物抵御病原体的过程中发挥作用。FST 蛋白的中央结构域与三种γ - 硫堇蛋白具有同源性。与其他硫堇蛋白前体一样，FST 蛋白具有一个信号肽特征的 N 端结构域和一个酸性的 C 端结构域。FST mRNA 特异性地在发育中的花朵中积累，并且随着花朵成熟其水平下降。转录本存在于花瓣、雄蕊和雌蕊中，但在萼片中无法检测到。原位杂交显示，FST mRNA 在花瓣近轴表面的表皮细胞以及心皮和花药壁的表面细胞层中最为丰富。如果 FST 蛋白确实在花朵中具有保护作用，那么 FST mRNA 的这种空间分布模式似乎能使它对两个内部生殖轮的这种作用最大化。文中讨论了 FST 可能的生物学作用。
