Departments of Molecular Biosciences and of Integrative Biology, Center for Computational Biology and Bioinformatics, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
1] Departments of Molecular Biosciences and of Integrative Biology, Center for Computational Biology and Bioinformatics, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA [2] State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Nat Commun. 2015 Jul 8;6:7453. doi: 10.1038/ncomms8453.
The genetic distance between hybridizing parents affects heterosis; however, the mechanisms for this remain unclear. Here we report that this genetic distance correlates with natural variation and epigenetic regulation of circadian clock-mediated stress responses. In intraspecific hybrids of Arabidopsis thaliana, genome-wide expression of many biotic and abiotic stress-responsive genes is diurnally repressed and this correlates with biomass heterosis and biomass quantitative trait loci. Expression differences of selected stress-responsive genes among diverse ecotypes are predictive of heterosis in their hybrids. Stress-responsive genes are repressed in the hybrids under normal conditions but are induced to mid-parent or higher levels under stress at certain times of the day, potentially balancing the tradeoff between stress responses and growth. Consistent with this hypothesis, repression of two candidate stress-responsive genes increases growth vigour. Our findings may therefore provide new criteria for effectively selecting parents to produce high- or low-yield hybrids.
杂交亲本间的遗传距离会影响杂种优势，但其中的机制尚不清楚。我们发现这种遗传距离与生物钟介导的应激反应的自然变异和表观遗传调控有关。在拟南芥的种内杂交中，许多生物和非生物胁迫响应基因的全基因组表达呈现昼夜节律抑制，这与生物量杂种优势和生物量数量性状位点相关。不同生态型间选择的应激响应基因的表达差异可以预测其杂种的杂种优势。在正常条件下，杂交种中的应激响应基因受到抑制，但在一天中的某些时间受到胁迫时，这些基因的表达会被诱导至中亲代或更高水平，从而在应激响应和生长之间取得平衡。这一假说与两个候选应激响应基因的抑制增加生长活力的结果一致。因此，我们的研究结果可能为有效选择产生高产或低产杂交种的亲本提供新的标准。
