Spontaneous homeotic mutants and genetic control of floral organ identity in a ranunculid
Spontaneous homeotic mutants and genetic control of floral organ identity in a ranunculid
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DOI：
10.1111/ede.12357
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发表时间：
2020-11-12
影响因子：
2.9
通讯作者：
Di Stilio, Veronica S.
中科院分区：
文献类型：
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作者：
Martinez-Gomez, Jesus;Galimba, Kelsey D.;Di Stilio, Veronica S.
利用正向遗传方法研究了五个非核心真双子叶植物Thalumtrum花器官同源异型突变体的花器官特性调控。我们假设这些突变体在花图案基因中携带缺陷。突变体的表征包括比较花的形态和器官的身份基因表达在早期和晚期的发展阶段，然后通过序列分析的编码和内含子区，以确定转录因子结合位点和蛋白质-蛋白质相互作用（PPI）的图案。突变体表现出改变的花MADS盒基因的表达，这进一步告知旁系同源物的功能所产生的基因复制中没有发现的参考模型系统。随后的突变体的修改的BCE模型支持新功能化的实例（例如，B类基因在萼片中异位表达）、部分冗余（E类）或旁系同源物的亚功能化（C类）。在候选花MADS盒基因的编码区中缺乏有害突变，表明顺式调节或反式作用突变在起作用。与这一假设相一致，双花突变体在AGAMOUS（AG）直系同源物的调节内含子中具有转座子插入或显示转座子活性的迹象。也发现了单个氨基酸取代，但它们没有落在任何鉴定的DNA结合或PPI基序上。总之，我们提出的证据表明，转座子的活性和调控突变的花同源异型基因可能是这些Thaltrum花同源异型突变体的显着表型的基础。
The regulation of floral organ identity was investigated using a forward genetic approach in five floral homeotic mutants of Thalictrum, a noncore eudicot. We hypothesized that these mutants carry defects in the floral patterning genes. Mutant characterization comprised comparative floral morphology and organ identity gene expression at early and late developmental stages, followed by sequence analysis of coding and intronic regions to identify transcription factor binding sites and protein-protein interaction (PPI) motifs. Mutants exhibited altered expression of floral MADS-box genes, which further informed the function of paralogs arising from gene duplications not found in reference model systems. The ensuing modified BCE models for the mutants supported instances of neofunctionalization (e.g., B-class genes expressed ectopically in sepals), partial redundancy (E-class), or subfunctionalization (C-class) of paralogs. A lack of deleterious mutations in the coding regions of candidate floral MADS-box genes suggested that cis-regulatory or trans-acting mutations are at play. Consistent with this hypothesis, double-flower mutants had transposon insertions or showed signs of transposon activity in the regulatory intron of AGAMOUS (AG) orthologs. Single amino acid substitutions were also found, yet they did not fall on any of the identified DNA binding or PPI motifs. In conclusion, we present evidence suggesting that transposon activity and regulatory mutations in floral homeotic genes likely underlie the striking phenotypes of these Thalictrum floral homeotic mutants.