Characterization of Linaria KNOX genes suggests a role in petal-spur development
Characterization of Linaria KNOX genes suggests a role in petal-spur development
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DOI：
10.1111/j.1365-313x.2011.04721.x
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发表时间：
2011-11-01
期刊：
影响因子：
7.2
通讯作者：
Glover, Beverley J.
中科院分区：
文献类型：
--
作者：
Box, Mathew S.;Dodsworth, Steven;Glover, Beverley J.
距是被子植物中反复进化的花被器官的管状突起。它们通常含有花蜜，并经常强烈影响传粉者的特异性，可能介导生殖隔离。金鱼草异位花瓣距突变体的鉴定表明，花瓣距的发育依赖于KNOTTED 1样同源框（KNOX）基因的表达，该基因因其在维持茎顶端分生组织中的作用而闻名。在这里，我们通过分离A. majus的KNOX基因Hirzina（AmHirz）和Invaginata（AmIna）。长有长而窄的花瓣距。我们将这些基因分别命名为LvHirz和LvIna。使用定量逆转录PCR，我们表明，LvHirz是在高水平的发展花瓣中表达，并证明花瓣相关的KNOX基因的表达是足以诱导囊状的产物在异源宿主的花瓣。我们提出了一个模型，其中KNOX基因的表达在早期花瓣，马刺发展促进和保持进一步的花瓣形态发生潜力，如前所述的KNOX基因在复叶发育的功能。这些数据表明，花瓣刺可能是通过调节基因表达的变化而进化的，这些变化导致快速和潜在的突变表型修饰。考虑到远缘类群中距个体发育的形态相似性，KNOX基因表达模式的变化可能是被子植物中距发育的共同特征。
Spurs are tubular outgrowths of perianth organs that have evolved iteratively among angiosperms. They typically contain nectar and often strongly influence pollinator specificity, potentially mediating reproductive isolation. The identification of Antirrhinum majus mutants with ectopic petal spurs suggested that petal-spur development is dependent on the expression of KNOTTED 1-like homeobox (KNOX) genes, which are better known for their role in maintaining the shoot apical meristem. Here, we tested the role of KNOX genes in petal-spur development by isolating orthologs of the A. majus KNOX genes Hirzina (AmHirz) and Invaginata (AmIna) from Linaria vulgaris, a related species that differs from A. majus in possessing long, narrow petal spurs. We name these genes LvHirz and LvIna, respectively. Using quantitative reverse-transcription PCR, we show that LvHirz is expressed at high levels in the developing petals and demonstrate that the expression of petal-associated KNOX genes is sufficient to induce sac-like outgrowths on petals in a heterologous host. We propose a model in which KNOX gene expression during early petal-spur development promotes and maintains further morphogenetic potential of the petal, as previously described for KNOX gene function in compound leaf development. These data indicate that petal spurs could have evolved by changes in regulatory gene expression that cause rapid and potentially saltational phenotypic modifications. Given the morphological similarity of spur ontogeny in distantly related taxa, changes in KNOX gene expression patterns could be a shared feature of spur development in angiosperms.