Arabidopsis HD-Zip II transcription factors control apical embryo development and meristem function
Arabidopsis HD-Zip II transcription factors control apical embryo development and meristem function
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DOI：
10.1242/dev.092833
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发表时间：
2013-05-15
期刊：
影响因子：
4.6
通讯作者：
Ruberti, Ida
中科院分区：
文献类型：
--
作者：
Turchi, Luana;Carabelli, Monica;Ruberti, Ida
拟南芥基因组编码10个同源结构域-亮氨酸拉链（HD-Zip）II蛋白。拟南芥HOMEOBOX 2（ATHB 2）、拟南芥HOMEOBOX 1（HAT 1）、HAT 2、HAT 3和ATHB 4受红光/远红光比率的变化调节，这在大多数被子植物中诱导避荫。在这里，我们表明，在白色光下，HAT 3，ATHB 4和ATHB 2活性的逐渐丧失会导致从胚胎发生开始的发育缺陷。hat 3 athb 4胚的子叶发育和数量发生改变，这些缺陷与生长素分布和反应的变化有关。athb 2功能获得性突变和由其在hat 3 athb 4中的启动子驱动的ATHB 2表达导致表型的显著减弱，从而证明ATHB 2相对于HAT 3和ATHB 4是功能冗余的。类似于HD-Zip III基因中的功能丧失突变，HAT 3和ATHB 4的丧失导致器官极性缺陷，而三重hat 3 athb 4 athb 2突变体发育一个或两个辐射状子叶并且缺乏活性的茎顶端分生组织（SAM）。与HD-Zip II和HD-Zip III基因家族成员的重叠表达模式一致，当hat 3 athb 4与PHABULOSA（PHB）、PHAVOLUTA（PHV）或REVOLUTA（REV）中的突变组合时，双侧对称性和SAM缺陷增强。最后，我们表明，ATHB 2是一个复杂的监管电路的一部分，直接涉及HD-Zip II和HD-Zip III蛋白。总而言之，我们的研究提供了证据，证明由HD-Zip II和HD-Zip III基因组成的遗传系统在建立双侧对称性和沿着胚胎近轴-远轴轴沿着形成图案以及控制SAM活性方面进行合作。
The Arabidopsis genome encodes ten Homeodomain-Leucine zipper (HD-Zip) II proteins. ARABIDOPSIS THALIANA HOMEOBOX 2 (ATHB2), HOMEOBOX ARABIDOPSIS THALIANA 1 (HAT1), HAT2, HAT3 and ATHB4 are regulated by changes in the red/far red light ratio that induce shade avoidance in most of the angiosperms. Here, we show that progressive loss of HAT3, ATHB4 and ATHB2 activity causes developmental defects from embryogenesis onwards in white light. Cotyledon development and number are altered in hat3 athb4 embryos, and these defects correlate with changes in auxin distribution and response. athb2 gain-of-function mutation and ATHB2 expression driven by its promoter in hat3 athb4 result in significant attenuation of phenotypes, thus demonstrating that ATHB2 is functionally redundant to HAT3 and ATHB4. In analogy to loss-of-function mutations in HD-Zip III genes, loss of HAT3 and ATHB4 results in organ polarity defects, whereas triple hat3 athb4 athb2 mutants develop one or two radialized cotyledons and lack an active shoot apical meristem (SAM). Consistent with overlapping expression pattern of HD-Zip II and HD-Zip III gene family members, bilateral symmetry and SAM defects are enhanced when hat3 athb4 is combined with mutations in PHABULOSA (PHB), PHAVOLUTA (PHV) or REVOLUTA (REV). Finally, we show that ATHB2 is part of a complex regulatory circuit directly involving both HD-Zip II and HD-Zip III proteins. Taken together, our study provides evidence that a genetic system consisting of HD-Zip II and HD-Zip III genes cooperates in establishing bilateral symmetry and patterning along the adaxial-abaxial axis in the embryo as well as in controlling SAM activity.