Wu Jian, Steinebrunner Iris, Sun Yu, Butterfield Timothy, Torres Jonathan, Arnold David, Gonzalez Antonio, Jacob Francis, Reichler Stuart, Roux Stanley J
Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712, USA.
Plant Physiol. 2007 Jun;144(2):961-75. doi: 10.1104/pp.107.097568. Epub 2007 Apr 13.
Expression of two Arabidopsis (Arabidopsis thaliana) apyrase (nucleoside triphosphate-diphosphohydrolase) genes with high similarity, APY1 and APY2, was analyzed during seedling development and under different light treatments using beta-glucuronidase fusion constructs with the promoters of both genes. As evaluated by beta-glucuronidase staining and independently confirmed by other methods, the highest expression of both apyrases was in rapidly growing tissues and/or tissues that accumulate high auxin levels. Red-light treatment of etiolated seedlings suppressed the protein and message level of both apyrases at least as rapidly as it inhibited hypocotyl growth. Adult apy1 and apy2 single mutants had near-normal growth, but apy1apy2 double-knockout plants were dwarf, due primarily to reduced cell elongation. Pollen tubes and etiolated hypocotyls overexpressing an apyrase had faster growth rates than wild-type plants. Growing pollen tubes released ATP into the growth medium and suppression of apyrase activity by antiapyrase antibodies or by inhibitors simultaneously increased medium ATP levels and inhibited pollen tube growth. These results imply that APY1 and APY2, like their homologs in animals, act to reduce the concentration of extracellular nucleotides, and that this function is important for the regulation of growth in Arabidopsis.
利用带有这两个基因启动子的β-葡萄糖醛酸酶融合构建体，分析了两个高度相似的拟南芥（Arabidopsis thaliana）焦磷酸酶（核苷三磷酸二磷酸水解酶）基因APY1和APY2在幼苗发育过程中以及不同光照处理下的表达情况。通过β-葡萄糖醛酸酶染色评估，并经其他方法独立验证，两种焦磷酸酶的最高表达均出现在快速生长的组织和/或生长素水平较高的组织中。对黄化幼苗进行红光处理，至少与抑制下胚轴生长一样迅速地抑制了两种焦磷酸酶的蛋白质和信使水平。成年apy1和apy2单突变体的生长接近正常，但apy1apy2双敲除植株矮小，主要原因是细胞伸长减少。过表达焦磷酸酶的花粉管和黄化下胚轴的生长速度比野生型植株快。生长中的花粉管将ATP释放到生长培养基中，抗焦磷酸酶抗体或抑制剂对焦磷酸酶活性的抑制同时增加了培养基中的ATP水平并抑制了花粉管生长。这些结果表明，APY1和APY2与其在动物中的同源物一样，起到降低细胞外核苷酸浓度的作用，并且该功能对于拟南芥生长的调节很重要。
