Cytokinins modulate auxin-induced organogenesis in plants via regulation of the auxin efflux
Cytokinins modulate auxin-induced organogenesis in plants via regulation of the auxin efflux
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DOI：
10.1073/pnas.0811539106
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发表时间：
2009-03-03
影响因子：
11.1
通讯作者：
Hejatko, Jan
中科院分区：
文献类型：
--
作者：
Pernisova, Marketa;Klima, Petr;Hejatko, Jan
胚后器官发生是植物进化出的一种重要的器官发生能力，它使植物的生理和发育适应不断变化的环境条件。植物激素生长素和细胞分裂素(CK)是多能植物细胞发育命运的重要调节因子。然而，它们相互作用的分子性质(S)在控制植物器官发生中的作用在很大程度上是未知的。在这里，我们表明，CK通过调节外排依赖的细胞间生长素分布来调节生长素诱导的器官发生(AIO)。我们使用基于下胚轴外植体的体外系统来研究器官发生的机制。我们发现生长素，而不是CK，能够触发下胚轴外植体的器官发生。AIO伴随着内源性CK的产生和CK信号的组织特异性激活。CK影响生长素的差异分布，CK介导的器官发生调控是通过抑制生长素的极性运输来模拟的。CK减少培养烟草细胞的生长素外流，并调节下胚轴外植体中来自PIN家族的生长素外流载体的表达。此外，内源CK水平影响PIN转录，是维持植物细胞间生长素分布所必需的。基于这些发现，我们提出了一个模型，在该模型中，生长素作为器官发生过程的触发器，其输出受到内源产生的CKS的调节。我们认为，CK作用的一个重要机制是通过调节生长素外排载体的表达而影响生长素的分布。
Postembryonic de novo organogenesis represents an important competence evolved in plants that allows their physiological and developmental adaptation to changing environmental conditions. The phytohormones auxin and cytokinin (CK) are important regulators of the developmental fate of pluripotent plant cells. However, the molecular nature of their interaction(s) in control of plant organogenesis is largely unknown. Here, we show that CK modulates auxin-induced organogenesis (AIO) via regulation of the efflux-dependent intercellular auxin distribution. We used the hypocotyl explants-based in vitro system to study the mechanism underlying de novo organogenesis. We show that auxin, but not CK, is capable of triggering organogenesis in hypocotyl explants. The AIO is accompanied by endogenous CK production and tissue-specific activation of CK signaling. CK affects differential auxin distribution, and the CK-mediated modulation of organogenesis is simulated by inhibition of polar auxin transport. CK reduces auxin efflux from cultured tobacco cells and regulates expression of auxin efflux carriers from the PIN family in hypocotyl explants. Moreover, endogenous CK levels influence PIN transcription and are necessary to maintain intercellular auxin distribution in planta. Based on these findings, we propose a model in which auxin acts as a trigger of the organogenic processes, whose output is modulated by the endogenously produced CKs. We propose that an important mechanism of this CK action is its effect on auxin distribution via regulation of expression of auxin efflux carriers.