Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet-Dagan 50250, Israel.
Plant Physiol. 2010 Dec;154(4):1929-56. doi: 10.1104/pp.110.160697. Epub 2010 Oct 14.
The abscission process is initiated by changes in the auxin gradient across the abscission zone (AZ) and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the molecular and biochemical basis of the increased AZ sensitivity to ethylene. We examined transcriptome changes in the tomato (Solanum lycopersicum 'Shiran 1335') flower AZ during the rapid acquisition of ethylene sensitivity following flower removal, which depletes the AZ from auxin, with or without preexposure to 1-methylcyclopropene or application of indole-3-acetic acid after flower removal. Microarray analysis using the Affymetrix Tomato GeneChip revealed changes in expression, occurring prior to and during pedicel abscission, of many genes with possible regulatory functions. They included a range of auxin- and ethylene-related transcription factors, other transcription factors and regulatory genes that are transiently induced early, 2 h after flower removal, and a set of novel AZ-specific genes. All gene expressions initiated by flower removal and leading to pedicel abscission were inhibited by indole-3-acetic acid application, while 1-methylcyclopropene pretreatment inhibited only the ethylene-induced expressions, including those induced by wound-associated ethylene signals. These results confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes resulting from auxin depletion. Our results shed light on the regulatory control of abscission at the molecular level and further expand our knowledge of auxin-ethylene cross talk during the initial controlling stages of the process.
离区的脱落过程由离区中生长素梯度的变化启动，并由乙烯触发。虽然基因表达的变化与乙烯介导的脱落执行有关，但关于增加的离区对乙烯敏感性的分子和生化基础几乎没有信息。我们检查了番茄（Solanum lycopersicum 'Shiran 1335'）花离区在去除花后快速获得乙烯敏感性期间的转录组变化，去除花会耗尽离区中的生长素，无论是否预先用 1-甲基环丙烯处理或在去除花后应用吲哚-3-乙酸。使用 Affymetrix Tomato GeneChip 的微阵列分析揭示了许多具有潜在调节功能的基因表达的变化，这些基因在花梗脱落之前和期间发生。它们包括一系列与生长素和乙烯相关的转录因子、其他转录因子和调节基因，这些基因在去除花后 2 小时被短暂诱导，还有一组新的离区特异性基因。去除花引起的所有基因表达并导致花梗脱落都被吲哚-3-乙酸的应用所抑制，而 1-甲基环丙烯预处理仅抑制了乙烯诱导的表达，包括与伤口相关的乙烯信号诱导的表达。这些结果证实了我们的假设，即离区中乙烯敏感性的获得与生长素耗竭导致生长素调节基因表达的改变有关。我们的结果揭示了脱落在分子水平上的调控控制，并进一步扩展了我们对生长素-乙烯相互作用在该过程初始控制阶段的知识。
