Temporal and spatial expression of a polygalacturonase during leaf and flower abscission in oilseed rape and Arabidopsis
Temporal and spatial expression of a polygalacturonase during leaf and flower abscission in oilseed rape and Arabidopsis
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DOI：
10.1104/pp.010610
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发表时间：
2002-02-01
期刊：
影响因子：
7.4
通讯作者：
Roberts, JA
中科院分区：
文献类型：
--
作者：
González-Carranza, ZH;Whitelaw, CA;Roberts, JA
在油菜叶片脱落过程中，细胞壁的降解是由几种水解酶的作用引起的。其中之一被认为是聚半乳糖醛酸酶（PG）。利用简并引物从乙烯促进叶片脱落区（AZs）提取的RNA中逆转录聚合酶链反应分离出PG cDNA片段，并从油菜叶片脱落区cDNA文库中分离出全长克隆（CAW471）。该cDNA的最高同源性（82%）是拟南芥序列，预计编码PG蛋白。表达分析表明，CAW471 mRNA在叶片AZ中积累，并在乙烯处理后24 h达到峰值。乙烯对油菜叶片脱落的促进作用在暴露于乙烯42 h后才显现出来，48 h时达到50%，56 h时达到100%。在花器官脱落中，CAW471的表达与细胞分离相关。用CAW471及其分离的基因组克隆PGAZBRAN和PGAZAT对油菜和拟南芥的基因组文库进行筛选。对这些PG基因的分析表明，它们在编码区和5'上游序列中具有相当的同源性。将PGAZAT上游1,476- 5'序列与β -葡糖醛酸酶或绿色荧光蛋白融合并转化到拟南芥中，发现该片段足以驱动这些报告基因在花药花丝、花瓣和萼片基部的AZs中表达。
During leaf abscission in oilseed rape (Brassica napus), cell wall degradation is brought about by the action of several hydrolytic enzymes. One of these is thought to be polygalacturonase (PG). Degenerate primers were used to isolate a PG cDNA fragment by reverse transcriptase-polymerase chain reaction from RNA extracted from ethylene-promoted leaf abscission zones (AZs), and in turn a full-length clone (CAW471) from an oilseed rape AZ cDNA library. The highest homology of this cDNA (82%) was to an Arabidopsis sequence that was predicted to encode a PG protein. Analysis of expression revealed that CAW471 mRNA accumulated in the AZ of leaves and reached a peak 24 h after ethylene treatment. Ethylene-promoted leaf abscission in oilseed rape was not apparent until 42 h after exposure to the gas, reaching 50% at 48 h and 100% by 56 h. In floral organ abscission, expression of CAW471 correlated with cell separation. Genomic libraries from oilseed rape and Arabidopsis were screened with CAW471 and the respective genomic clones PGAZBRAN and PGAZAT isolated. Characterization of these PG genes revealed that they had substantial homology within both the coding regions and in the 5'-upstream sequences. Fusion of a 1,476-by 5'-upstream sequence of PGAZAT to beta-glucuronidase or green fluorescent protein and transformation of Arabidopsis revealed that this fragment was sufficient to drive expression of these reporter genes in the AZs at the base of the anther filaments, petals, and sepals.