Borner R, Kampmann G, Chandler J, Gleissner R, Wisman E, Apel K, Melzer S
Swiss Federal Institute of Technology, Institute for Plant Sciences, Universitätstrasse 2, CH-8092 Zürich, Switzerland.
Plant J. 2000 Dec;24(5):591-9. doi: 10.1046/j.1365-313x.2000.00906.x.
Flowering time in many plants is triggered by environmental factors that lead to uniform flowering in plant populations, ensuring higher reproductive success. So far, several genes have been identified that are involved in flowering time control. AGL20 (AGAMOUS LIKE 20) is a MADS domain gene from Arabidopsis that is activated in shoot apical meristems during the transition to flowering. By transposon tagging we have identified late flowering agl20 mutants, showing that AGL20 is involved in flowering time control. In previously described late flowering mutants of the long-day and constitutive pathways of floral induction the expression of AGL20 is down-regulated, demonstrating that AGL20 acts downstream to the mutated genes. Moreover, we can show that AGL20 is also regulated by the gibberellin (GA) pathway, indicating that AGL20 integrates signals of different pathways of floral induction and might be a central component for the induction of flowering. In addition, the constitutive expression of AGL20 in Arabidopsis is sufficient for photoperiod independent flowering and the over-expression of the orthologous gene from mustard, MADSA, in the classical short-day tobacco Maryland Mammoth bypasses the strict photoperiodic control of flowering.
许多植物的开花时间由环境因素触发，这些因素导致植物群体中花朵同时开放，从而确保更高的繁殖成功率。到目前为止，已经鉴定出几个参与开花时间控制的基因。AGL20（类AGAMOUS 20）是来自拟南芥的一个MADS结构域基因，在向开花转变过程中于茎尖分生组织中被激活。通过转座子标签法，我们鉴定出了开花延迟的agl20突变体，表明AGL20参与开花时间控制。在先前描述的长日和组成型开花诱导途径的开花延迟突变体中，AGL20的表达下调，这表明AGL20在突变基因的下游起作用。此外，我们能够证明AGL20也受赤霉素（GA）途径调控，这表明AGL20整合了不同开花诱导途径的信号，可能是开花诱导的核心组分。另外，AGL20在拟南芥中的组成型表达足以实现不依赖光周期的开花，并且来自芥菜的直系同源基因MADSA在经典短日烟草马里兰猛犸中的过表达绕过了对开花的严格光周期控制。
