Variation in the flowering time orthologs BrFLC and BrSOC1 in a natural population of Brassica rapa
Variation in the flowering time orthologs BrFLC and BrSOC1 in a natural population of Brassica rapa
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DOI：
10.7717/peerj.1339
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发表时间：
2015-11-30
期刊：
影响因子：
2.7
通讯作者：
Litt, Amy
中科院分区：
文献类型：
--
作者：
Franks, Steven J.;Perez-Sweeney, Beatriz;Litt, Amy
理解自然表型变异的遗传基础是非常重要的，特别是因为选择可以作用于这种变异而导致进化。我们研究了来自自然种群的芜菁植物中候选开花时间位点的表达和等位基因变异，并显示出第一次开花时间的广泛范围。感兴趣的基因座是拟南芥基因FLC和SOC1（分别为BrFLC和BrSOC1）的直系同源物，其在拟南芥中在开花时间调控网络中起核心作用，FLC抑制和SOC1促进开花。在B。rapa中，FLC有四个拷贝，SOC 1有三个拷贝。植物在实验室的受控条件下生长。在最早开花和最晚开花的植物之间进行了比较，这些组之间的平均开花时间差异接近30天。正如预期的那样，我们发现BrSOC1旁系同源物的总表达量在开花早的植物中显著高于开花晚的植物。旁系同源物特异性引物显示，表达是更大的BrSOC1旁系同源物Br004928，Br00393和Br009324中的早开花植物，虽然在Br009324中的差异不显着。因此，至少有2的3个BrSOC1直系同源物的表达是一致的预测作用，在开花时间在这个自然群体。BrSOC1同源基因的启动子区域的序列是可变的，但在这些位点的等位基因变异和开花时间变异之间没有关联。对于BrFLC直系同源物，表达随时间变化，但在早花和晚花植物之间没有差异。这些基因的编码区、启动子区和内含子一般是不变的。因此，BrFLC直系同源物似乎不影响该群体中的开花时间。总的来说，研究结果表明，即使是像开花时间这样由一个非常好的遗传调控网络控制的性状，理解这种数量性状自然变异的潜在遗传基础也是具有挑战性的。
Understanding the genetic basis of natural phenotypic variation is of great importance, particularly since selection can act on this variation to cause evolution. We examined expression and allelic variation in candidate flowering time loci in Brassica rapa plants derived from a natural population and showing a broad range in the timing of first flowering. The loci of interest were orthologs of the Arabidopsis genes FLC and SOC1 (BrFLC and BrSOC1, respectively), which in Arabidopsis play a central role in the flowering time regulatory network, with FLC repressing and SOC1 promoting flowering. In B. rapa, there are four copies of FLC and three of SOC1. Plants were grown in controlled conditions in the lab. Comparisons were made between plants that flowered the earliest and latest, with the difference in average flowering time between these groups similar to 30 days. As expected, we found that total expression of BrSOC1 paralogs was significantly greater in early than in late flowering plants. Paralog-specific primers showed that expression was greater in early flowering plants in the BrSOC1 paralogs Br004928, Br00393 and Br009324, although the difference was not significant in Br009324. Thus expression of at least 2 of the 3 BrSOC1 orthologs is consistent with their predicted role in flowering time in this natural population. Sequences of the promoter regions of the BrSOC1 orthologs were variable, but there was no association between allelic variation at these loci and flowering time variation. For the BrFLC orthologs, expression varied over time, but did not differ between the early and late flowering plants. The coding regions, promoter regions and introns of these genes were generally invariant. Thus the BrFLC orthologs do not appear to influence flowering time in this population. Overall, the results suggest that even for a trait like flowering time that is controlled by a very well described genetic regulatory network, understanding the underlying genetic basis of natural variation in such a quantitative trait is challenging.