Auxin controls petal initiation in Arabidopsis
Auxin controls petal initiation in Arabidopsis
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DOI：
10.1242/dev.084582
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发表时间：
2013-01-01
期刊：
影响因子：
4.6
通讯作者：
Smyth, David R.
中科院分区：
文献类型：
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作者：
Lampugnani, Edwin R.;Kilinc, Aydin;Smyth, David R.
花器官通常排列成萼片、花瓣、雄蕊和心皮的同心轮生体。这些器官的创始细胞是如何被指定的尚不清楚。在拟南芥中，花瓣丢失 (PTL) 转录因子在萼片轮中发挥作用，限制萼片间区域的大小。遗传证据表明 PTL 的作用是支持邻近轮生中活跃的花瓣起始信号。在这里，我们的目的是通过鉴定破坏 ptl 突变体中剩余花瓣起始的增强子来表征信号。其中一种增强子编码生长素流入蛋白 AUX1。我们通过促进 ptl 突变植物萼片间区域的生物合成并恢复附近的花瓣起始，确定生长素是一种直接且可移动的花瓣起始信号。与此一致的是，PTL 功能的丧失会破坏 DR5 的表达，DR5 是花瓣起始位点的生长素诱导指标。该信号网络通过以下证明得以扩展：(1) 兔耳 (RBE) 功能的丧失明显破坏了与 PTL 相同的生长素流入过程； (2) AUX1的作用得到AXR4的支持，AXR4是其在生长素流入中的上游伙伴； (3)极性生长素转运，由PINOID (PID)和PIN-FORMED1 (PIN1)控制，在PTL下游发挥作用； (4) pmd-1d（ptl突变体表型的显性修饰剂）的作用依赖于生长素转运。因此，PTL 功能的丧失会扰乱生长素动力学，从而揭示生长素在促进花瓣形成中的作用。
Floral organs are usually arranged in concentric whorls of sepals, petals, stamens and carpels. How founder cells of these organs are specified is unknown. In Arabidopsis, the PETAL LOSS (PTL) transcription factor functions in the sepal whorl, where it restricts the size of the inter-sepal zone. Genetic evidence suggests that PTL acts to support a petal initiation signal active in the adjacent whorl. Here we aimed to characterise the signal by identifying enhancers that disrupt initiation of the remaining petals in ptl mutants. One such enhancer encodes the auxin influx protein AUX1. We have established that auxin is a direct and mobile petal initiation signal by promoting its biosynthesis in the inter-sepal zone in ptl mutant plants and restoring nearby petal initiation. Consistent with this, loss of PTL function disrupts DR5 expression, an auxin-inducible indicator of petal-initiation sites. The signalling network was extended by demonstrating that: (1) loss of RABBIT EARS (RBE) function apparently disrupts the same auxin influx process as PTL; (2) the action of AUX1 is supported by AXR4, its upstream partner in auxin influx; (3) polar auxin transport, which is controlled by PINOID (PID) and PIN-FORMED1 (PIN1), functions downstream of PTL; and (4) the action of pmd-1d, a dominant modifier of the ptl mutant phenotype, is dependent on auxin transport. Thus, loss of PTL function disrupts auxin dynamics, allowing the role of auxin in promoting petal initiation to be revealed.