The Roles of the Sole Activator-Type Auxin Response Factor in Pattern Formation of Marchantia polymorpha
The Roles of the Sole Activator-Type Auxin Response Factor in Pattern Formation of Marchantia polymorpha
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DOI：
10.1093/pcp/pcx095
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发表时间：
2017-10-01
影响因子：
4.9
通讯作者：
Kohchi, Takayuki
中科院分区：
文献类型：
--
作者：
Kato, Hirotaka;Kouno, Masaru;Kohchi, Takayuki
细胞分裂模式是决定植物体型的重要因素。生长素应答因子（auxin RESPONSE FACTOR， ARF）转录因子介导的核生长素信号通过调控细胞的分裂、伸长和分化来影响植物的生长发育。arf介导途径的进化起源至少可以追溯到苔藓植物和其他陆地植物的共同祖先。地茅（Marchantia polymorpha）有三个系统发育上不同的ARF: MpARF1，唯一的“激活因子”ARF；以及MpARF2和MpARF3这两种“抑制”arf。生长素抗性突变体的遗传筛选显示，MpARF1功能的丧失导致生长素不敏感。Mparf1突变体表现出生长素诱导基因表达减少和各种发育缺陷，包括菌体扭曲和胚芽畸形。我们进一步研究了MpARF1在gemma发育中的作用，这可以追溯到细胞水平。在野生型植物中，胚芽最初经历几个横向分裂，产生单细胞茎和胚芽，然后在后者中进行相当同步的纵向分裂。Mparf1突变体通常含有多细胞茎，并在纵向分裂的执行和时间上表现出缺陷。野生型胚芽最终产生两个分生组织缺口，而Mparf1胚芽则表现出不同数量的异位分生组织。这些结果表明MpARF1通过生长素反应调节形成性细胞分裂和轴的形成。激活剂ARF调控图案形成的机制可能在陆地植物中是共享的，因此对三维身体平面图的一般获取很重要。
Cell division patterning is important to determine body shape in plants. Nuclear auxin signaling mediated by AUXIN RESPONSE FACTOR (ARF) transcription factors affects plant growth and development through regulation of cell division, elongation and differentiation. The evolutionary origin of the ARF-mediated pathway dates back to at least the common ancestor of bryophytes and other land plants. The liverwort Marchantia polymorpha has three phylogenetically distinct ARFs: MpARF1, the sole 'activator' ARF; and MpARF2 and MpARF3, two 'repressor' ARFs. Genetic screens for auxin-resistant mutants revealed that loss of MpARF1 function conferred auxin insensitivity. Mparf1 mutants showed reduced auxin-inducible gene expression and various developmental defects, including thallus twisting and gemma malformation. We further investigated the role of MpARF1 in gemma development, which is traceable at the cellular level. In wild-type plants, a gemma initial first undergoes several transverse divisions to generate a single-celled stalk and a gemma proper, followed by rather synchronous longitudinal divisions in the latter. Mparf1 mutants often contained multicelled stalks and showed defects in the execution and timing of the longitudinal divisions. While wild-type gemmae finally generate two meristem notches, Mparf1 gemmae displayed various numbers of ectopic meristems. These results suggest that MpARF1 regulates formative cell divisions and axis formation through auxin responses. The mechanism for activator ARF regulation of pattern formation may be shared in land plants and therefore important for the general acquisition of three-dimensional body plans.