Pezzotti Mario, Feron Richard, Mariani Celestina
Plant Genetic Systems, Gent, Belgium.
Plant Mol Biol. 2002 May;49(2):187-97. doi: 10.1023/a:1014962923278.
Using differential screening we isolated a pistil-specific cDNA clone corresponding to a 1.2 kb mRNA and encoding a 32.5 kDa protein. The amino acid sequence shared similarity with that of group-I grass pollen allergens, which are known to have expansin activity. This clone, which later showed to share homology also with beta-expansins, was named PPAL. The PPAL mRNA was specifically expressed in the secretory zone of the stigma and in the epidermal layer of the placenta. The accumulation level of the transcript increased during pollination, and the protein was secreted in the stigmatic exudate of the tobacco flower. We suggest here that PPAL is a new expansin, acting as a cell-wall-loosening agent during pollination.
利用差异筛选，我们分离出了一个雌蕊特异性cDNA克隆，它对应于一个1.2 kb的mRNA，编码一种32.5 kDa的蛋白质。该氨基酸序列与I类禾本科花粉过敏原的氨基酸序列具有相似性，已知这些过敏原具有扩张蛋白活性。这个克隆后来还显示与β-扩张蛋白具有同源性，被命名为PPAL。PPAL mRNA在柱头的分泌区和胎座的表皮层中特异性表达。授粉期间转录本的积累水平增加，并且该蛋白质分泌到烟草花的柱头渗出物中。我们在此提出，PPAL是一种新的扩张蛋白，在授粉过程中作为细胞壁松弛剂发挥作用。
