Wang Xutong, Zhang Huakun, Li Yaling, Zhang Zhibin, Li Linfeng, Liu Bao
Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
Department of Biology, Washington University in St Louis, St Louis, MO, 63130, USA.
New Phytol. 2016 Feb;209(3):1264-77. doi: 10.1111/nph.13678. Epub 2015 Oct 5.
Allopolyploidization has occurred frequently within the Triticum-Aegilops complex which provides a suitable system to investigate how allopolyploidization shapes the expression patterns of duplicated homeologs. We have conducted transcriptome-profiling of leaves and young inflorescences in wild and domesticated tetraploid wheats, Triticum turgidum ssp. dicoccoides (BBAA) and ssp. durum (BBAA), an extracted tetraploid (BBAA), and a synthetic tetraploid (S(l) S(l) AA) wheat together with its diploid parents, Aegilops longissima (S(l) S(l) ) and Triticum urartu (AA). The two diploid species showed tissue-specific differences in genome-wide ortholog expression, which plays an important role in transcriptome shock-mediated homeolog expression rewiring and hence transcriptome asymmetry in the synthetic tetraploid. Further changes of homeolog expression apparently occurred in natural tetraploid wheats, which led to novel transcriptome asymmetry between the two subgenomes. In particular, our results showed that extremely biased homeolog expression can occur rapidly upon the allotetraploidzation and this trend is further enhanced in the course of domestication and evolution of polyploid wheats. Our results suggest that allopolyploidization is accompanied by distinct phases of homeolog expression changes, with parental legacy playing major roles in the immediate rewiring of homeolog expression upon allopolyploidization, while evolution and domestication under allotetraploidy drive further homeolog-expression changes toward re-established subgenome expression asymmetry.
异源多倍体化在小麦 - 山羊草复合体中频繁发生，这为研究异源多倍体化如何塑造重复同源基因的表达模式提供了一个合适的系统。我们对野生和驯化的四倍体小麦、硬粒小麦亚种（BBAA）和二粒小麦亚种（BBAA）、一个提取的四倍体（BBAA）以及一个人工合成四倍体（S(l) S(l) AA）小麦及其二倍体亲本长穗山羊草（S(l) S(l) ）和乌拉尔图小麦（AA）的叶片和幼嫩花序进行了转录组分析。这两个二倍体物种在全基因组直系同源基因表达上表现出组织特异性差异，这在转录组冲击介导的同源基因表达重排以及因此在人工合成四倍体中的转录组不对称性中起着重要作用。同源基因表达的进一步变化显然发生在天然四倍体小麦中，这导致了两个亚基因组之间新的转录组不对称性。特别是，我们的结果表明，异源四倍体化后同源基因表达会迅速出现极端偏向，并且在多倍体小麦的驯化和进化过程中这种趋势会进一步增强。我们的结果表明，异源多倍体化伴随着同源基因表达变化的不同阶段，亲本遗传在异源多倍体化后同源基因表达的直接重排中起主要作用，而异源四倍体下的进化和驯化则推动同源基因表达进一步变化，朝着重新建立的亚基因组表达不对称性发展。
