The NAC-domain transcription factor GOBLET specifies leaflet boundaries in compound tomato leaves
The NAC-domain transcription factor GOBLET specifies leaflet boundaries in compound tomato leaves
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DOI：
10.1242/dev.031625
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发表时间：
2009-03-01
期刊：
影响因子：
4.6
通讯作者：
Ori, Naomi
中科院分区：
文献类型：
--
作者：
Berger, Yael;Harpaz-Saad, Smadar;Ori, Naomi
叶在茎顶端分生组织（SAM）的侧面形成，并发育成各种形式。在番茄中，延长的叶型使得复叶能够通过具有浅裂边缘的小叶的反复起始而形成。在杯状（gob）功能丧失突变体中，初级小叶通常融合，次级小叶和边缘锯齿缺失，SAM通常过早终止。我们发现，GOB编码的NAC结构域转录因子表达在叶缘窄条纹，侧翼未来小叶原基的远端侧，并在SAM和叶原基之间的边界。微小RNA miR164（GOB样基因的负调节因子）的叶特异性过表达也导致次级小叶起始的丧失和平滑小叶边缘。携带具有完整ORF但破坏miR164结合位点的显性gob等位基因的植物产生更多的子叶和花器官，具有分裂的SAM，并且令人惊讶地，具有更简单的叶。在叶原基中具有改变的miR164结合位点的GOB形式的过表达导致延迟的小叶成熟、频繁的、不适当的时间和间隔的起始事件以及由于次级小叶融合而导致的简单的成熟小叶形式。miR164还影响碎米荠（Cardamine hirsuta）的小叶分离，碎米荠是具有复杂叶的菊科物种。遗传和分子分析表明，GOB的表达是完整的简化叶的整个番茄突变体，其中有一个缺陷，在一个假定的阻遏生长素反应。我们的研究结果表明，GOB标记小叶边界，其准确的空间，时间和定量的活动影响叶加工在一个上下文相关的方式。
Leaves are formed at the flanks of the shoot apical meristem (SAM) and develop into a variety of forms. In tomato, prolonged leaf patterning enables the elaboration of compound leaves by reiterative initiation of leaflets with lobed margins. In goblet (gob) loss-of-function mutants, primary leaflets are often fused, secondary leaflets and marginal serrations are absent, and SAMs often terminate precociously. We show that GOB encodes a NAC-domain transcription factor expressed in narrow stripes at the leaf margins, flanking the distal side of future leaflet primordia, and at the boundaries between the SAM and leaf primordia. Leaf-specific overexpression of the microRNA miR164, a negative regulator of GOB-like genes, also leads to loss of secondary-leaflet initiation and to smooth leaflet margins. Plants carrying a dominant gob allele with an intact ORF but disrupted miR164 binding site produce more cotyledons and floral organs, have split SAMs and, surprisingly, simpler leaves. Overexpression of a form of GOB with an altered miR164 binding site in leaf primordia leads to delayed leaflet maturation, frequent, improperly timed and spaced initiation events, and a simple mature leaflet form owing to secondary-leaflet fusion. miR164 also affects leaflet separation in Cardamine hirsuta, a Brassicaceae species with complex leaves. Genetic and molecular analyses suggest that GOB expression is intact in the simplified leaves of entire tomato mutants, which have a defect in a putative repressor of auxin responses. Our results show that GOB marks leaflet boundaries and that its accurate spatial, temporal and quantitative activity affects leaf elaboration in a context-dependent manner.