Dosage-dependent regulation in hybridization

描述（申请人提供）：形成植物的倍性或种间杂种的困难证明了亲本匹配在繁殖中的重要性。“不平衡”的亲本贡献导致种子失败。有趣的是，平衡是一种遗传性状，而不仅仅是基因组剂量的结果，因为某些二倍体可以比其他二倍体物种更好地与四倍体物种匹配。我们推测，染色质和生长的调节是剂量敏感的过程，影响植物杂交的成功。这一假设得到了以下初步观察的支持：具有相同基因型的拟南芥亲本产生死亡或存活的杂交种子，这取决于亲本基因组比例。来自种间杂交的种子显示异染色质重复ATHILA和印迹的父系表达的转录因子PHE1的剂量依赖性去阻遏。PHE1活性降低抑制种间杂交中的死亡。利用亲本剂量潜力的遗传变异，我们已经表征了倍性和种间杂交的遗传学，发现两者都受少数QTL控制。母体对倍性间杂交的敏感性响应于转录调节因子TTG 2，其在母体组织中起作用以调节胚乳生长。TTG2活性降低导致种子存活，并可能解释观察到的主效应QTL。基于这些结果，我们建议：1。确定影响种间和倍性间合子后不亲和性的QTL的分子基础。2.研究种间和倍性间交配中不匹配配子融合的转录结果。3.调查ATHILA和PHERES 1错误表达的原因和后果以及不相容的发育后果。拟议的研究将填补空白，在我们的理解，在植物中的合子后兼容性的因素，并帮助解决染色质和生长调节剂的功能，剂量敏感的组件。虽然非整倍体，基因组元素的不平衡剂量，与癌症有关，并导致几种遗传疾病，如唐氏综合症，但很难在人类中研究其分子基础。植物拟南芥提供了一个机会，剖析剂量决定因素的模式真核生物。本研究获得的知识可能有助于了解剂量相关疾病，并可能有助于预防和治疗。

DESCRIPTION (provided by applicant): The difficulty of forming interploidy or interspecies hybrids of plants demonstrates the importance of matched parents in reproduction. "Unbalanced" parental contributions cause seed failure. Interestingly, balance is a genetic trait and not only a consequence of genome dosage, as certain diploids can be better matched with tetraploid species than with other diploid species. We hypothesize that regulation of chromatin and growth are dosage-sensitive processes that affect the success of plant hybridization. This hypothesis is supported by the following preliminary observations: Arabidopsis parents with identical genotypes produce dead or viable hybrid seeds depending on the parental genomic ratio. Seeds from interspecific crosses display dosage-dependent derepression of the heterochromatic repeat ATHILA, and of the imprinted, paternally- expressed, transcription factor PHE1. Decreased activity of PHE1 suppresses death in interspecific crosses. Using genetic variation in parental dosage potential, we have characterized the genetics of interploidy and interspecies hybridization finding that both are controlled by few QTL. Maternal sensitivity to interploidy crosses responds to the transcription regulator TTG2, which acts in maternal tissue to modulate endosperm growth. Decreased activity of TTG2 results in seed survival and is likely to explain an observed major effect QTL. Based on these results, we propose to: 1. Determine the molecular basis of QTL affecting interspecific and interploidy postzygotic incompatibility. 2. Investigate the transcriptional consequences of the fusion of mismatched gametes in both interspecific and interploidy matings. 3. Investigate the causes and consequences of ATHILA and PHERES1 misexpression and the developmental consequences of incompatibility. The proposed research will fill a lacuna in our understanding of factors governing postzygotic compatibility in plants and help address the function of chromatin and growth regulators as dosage sensitive components. Although aneuploidy, the unbalanced dosage of genomic elements, is associated with cancer and causes several genetic diseases such as Down Syndrome, it is difficult to study its molecular basis in humans. The plant Arabidopsis provides the opportunity to dissect dosage determinants in a model eukaryote. The knowledge gained in this study may help understand dosage-related diseases and possibly help in their prevention and treatment.