Cho H T, Kende H
Michigan State University, Department of Energy Plant Research Laboratory, Michigan State University, East Lansing 48824-1312, USA.
Plant Cell. 1997 Sep;9(9):1661-71. doi: 10.1105/tpc.9.9.1661.
Expansins are a family of proteins that catalyze long-term extension of isolated cell walls. Previously, two expansin proteins have been isolated from internodes of deepwater rice, and three rice expansin genes, Os-EXP1, Os-EXP2, and Os-EXP3, have been identified. We report here on the identification of a fourth rice expansin gene, Os-EXP4, and on the expression pattern of the rice expansin gene family in deepwater rice. Rice expansin genes show organ-specific differential expression in the coleoptile, root, leaf, and internode. In these organs, there is increased expression of Os-EXP1, Os-EXP3, and Os-EXP4 in developmental regions where elongation occurs. This pattern of gene expression is also correlated with acid-induced in vitro cell wall extensibility. Submergence and treatment with gibberellin, both of which promote rapid internodal elongation, induced accumulation of Os-EXP4 mRNA before the rate of growth started to increase. Our results indicate that the expression of expansin genes in deepwater rice is differentially regulated by developmental, hormonal, and environmental signals and is correlated with cell elongation.
扩张蛋白是一类能催化离体细胞壁长期伸展的蛋白质家族。此前，已从深水水稻的节间中分离出两种扩张蛋白，并且鉴定出了三个水稻扩张蛋白基因，即Os-EXP1、Os-EXP2和Os-EXP3。我们在此报告了第四个水稻扩张蛋白基因Os-EXP4的鉴定以及水稻扩张蛋白基因家族在深水水稻中的表达模式。水稻扩张蛋白基因在胚芽鞘、根、叶和节间呈现器官特异性差异表达。在这些器官中，Os-EXP1、Os-EXP3和Os-EXP4在发生伸长的发育区域表达增加。这种基因表达模式也与酸诱导的体外细胞壁伸展性相关。淹水和赤霉素处理均能促进节间快速伸长，二者在生长速率开始增加之前均诱导了Os-EXP4 mRNA的积累。我们的结果表明，深水水稻中扩张蛋白基因的表达受发育、激素和环境信号的差异调节，并且与细胞伸长相关。
