The Regulatory Disruption Hypothesis for Heterosis

Pi：Luca Comai(加州大学戴维斯分校)Copi：Vladimir Filkov(加州大学戴维斯分校)杂种优势定义了杂交后代比近交系亲本表现出的更强的活力。它的分子基础还不清楚，除了父母之间的遗传差异可能是原因。这项工作解决了以下假说：“杂交种受到调控障碍，是因为父母对调控复合体的贡献在结构或数量上不匹配。宽松的调控会激活导致生长增强的途径。”为了验证这一假设，将使用杂交水稻来研究RNA丰度、等位基因贡献和染色质状态。其目的是：(I)比较进化距离对双亲和杂交表达差异和亲本表达偏好的影响；(Ii)将表达变化与启动子活性和抑制染色质状态的变化联系起来；以及(Iii)检查杂交对调控网络的影响，以确定与生长相关的基因是否是杂交误调控的靶标。这项分析将需要一种名为cDNA-Rescan的新技术来以有效的成本区分父母表达的贡献，并将使用一个生物信息学和计算团队来剖析调控层次结构。通过探索一个特定的杂种优势假说，这项工作将为杂交种的整体调控效应提供重要信息。由于生物系统是水稻，是最被理解的草基因组，也是全球最重要的粮食作物，所获得的知识可能会影响我们对细胞功能的基本理解，以及对可能影响小麦、玉米和其他美国经济关键作物产量的途径的分子理解。这项研究的教育部分将涉及对来自当地和代表性不足社区的本科生的培训。数据将在NIH GEO表达数据库和实验室网站(http://comailab.genomecenter.ucdavis.edu/).)上提供

PI: Luca Comai (University of California, Davis)CoPI: Vladimir Filkov (University of California, Davis)Heterosis defines the increased vigor displayed by hybrid progeny compared to the inbred parents. Its molecular basis is not understood, except that genetic differences between parents are the likely cause. This work addresses the following hypothesis: "Hybrids suffer regulatory impairment because the parental contribution to regulatory complexes is mismatched in structure or amount. Relaxed regulation results in activation of pathways that cause enhanced growth". To test this hypothesis, RNA abundance, allelic contribution, and chromatin state will be investigated using hybrids of rice. The objectives are to: (i) compare the effect of evolutionary distance on parents and hybrid expression differences and parental expression preference; (ii) correlate expression changes to promoter activity and changes in repressive chromatin state, and (iii) examine the effects of hybridity on regulatory networks to determine if genes associated with growth are targets of hybrid misregulation. This analysis will entail a novel technology called cDNA-RESCAN to distinguish parental expression contributions at an effective cost, and will employ a bioinformatic and computational team for dissection of regulatory hierarchies. By exploring a specific hypothesis of heterosis, this work will provide important information on the overall regulatory effect of hybridity. Because the biological system is rice, the best understood grass genome and globally, the most important food crop, the acquired knowledge is likely to impact both our basic understanding of cellular function and the molecular understanding of pathways that may affect yield in wheat, maize and other critical crops for the US economy. Educational components of this research will involve training of undergraduates from local and from under-represented communities. Data will be made available on the NIH GEO expression database, and the laboratory website (http://comailab.genomecenter.ucdavis.edu/).