The Conserved Chimeric Transcript UPGRADE2 Is Associated with Unreduced Pollen Formation and Is Exclusively Found in Apomictic Boechera Species
The Conserved Chimeric Transcript UPGRADE2 Is Associated with Unreduced Pollen Formation and Is Exclusively Found in Apomictic Boechera Species
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DOI：
10.1104/pp.113.222448
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发表时间：
2013-12-01
期刊：
影响因子：
7.4
通讯作者：
Sharbel, Timothy F.
中科院分区：
文献类型：
--
作者：
Mau, Martin;Corral, Jose M.;Sharbel, Timothy F.
在无融合生殖的Boechera spp.中，减数分裂倍数孢子体形成导致减数分裂的规避和重组的抑制以产生未减数的雄性和雌性配子（即，无减数分裂）。在这里，我们已经建立了一个早期的花发育分期系统，并进行了基于微阵列的比较基因表达分析的花粉母细胞阶段在7个二倍体有性和7个二倍体无融合生殖基因型，以确定候选因素的未减少花粉形成。我们鉴定了无融合生殖Boechera spp.称为UPGRADE2（BspUPG2），在花粉母细胞中高度上调。BspUPG2在无融合生殖的Boechera spp.基因型，但没有同源性的有性Boechera spp。或任何其他分类群。BspUPG2经历转录后加工，但缺乏突出的开放阅读框架。结合稳定形成microRNA样二级结构的潜力，我们假设BspUPG2作为一种长的调节性非编码信使RNA样RNA发挥作用。BspUPG2显然是通过三步过程产生的，这三步过程由原始BspUPG1位点的祖先基因复制开始，然后是连续插入片段复制的基因片段，最后是其序列结构的外显子化。它的起源反映了杂交历史的特点属Boechera。
In apomictic Boechera spp., meiotic diplospory leads to the circumvention of meiosis and the suppression of recombination to produce unreduced male and female gametes (i.e. apomeiosis). Here, we have established an early flower developmental staging system and have performed microarray-based comparative gene expression analyses of the pollen mother cell stage in seven diploid sexual and seven diploid apomictic genotypes to identify candidate factors for unreduced pollen formation. We identified a transcript unique to apomictic Boechera spp. called UPGRADE2 (BspUPG2), which is highly up-regulated in their pollen mother cells. BspUPG2 is highly conserved among apomictic Boechera spp. genotypes but has no homolog in sexual Boechera spp. or in any other taxa. BspUPG2 undergoes posttranscriptional processing but lacks a prominent open reading frame. Together with the potential of stably forming microRNA-like secondary structures, we hypothesize that BspUPG2 functions as a long regulatory noncoding messenger RNA-like RNA. BspUPG2 has apparently arisen through a three-step process initiated by ancestral gene duplication of the original BspUPG1 locus, followed by sequential insertions of segmentally duplicated gene fragments, with final exonization of its sequence structure. Its genesis reflects the hybridization history that characterizes the genus Boechera.