Dosage-dependent regulation in hybridization

描述(由申请人提供)：形成植物的倍性或种间杂交的困难证明了配对亲本在繁殖中的重要性。“不平衡”的父母贡献会导致种子失败。有趣的是，平衡是一种遗传特征，而不仅仅是基因组剂量的结果，因为某些二倍体与四倍体物种比与其他二倍体物种更匹配。我们假设染色质和生长的调节是影响植物杂交成功的剂量敏感过程。这一假说得到了以下初步观察的支持：具有相同基因类型的拟南芥亲本产生死亡或存活的杂交种子取决于亲本基因组比例。来自种间杂交的种子表现出剂量依赖的异色重复ATHILA和印记的父系表达的转录因子PHE1的去表达。PHE1活性的降低抑制了种间杂交的死亡。利用亲本剂量潜力的遗传变异，我们对二倍体和种间杂交的遗传学进行了表征，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控因子TTG2，TTG2在母体组织中作用于调节胚乳生长。TTG2活性降低导致种子存活，并可能解释观察到的主要效应QTL。基于这些结果，我们建议：1.确定影响种间和倍性合子后不亲和性的QTL的分子基础。2.研究种间配子和倍性配子错配融合的转录后果。3.研究ATHILA和PHERES1错误表达的原因和后果，以及不相容的发育后果。这项拟议的研究将填补我们对控制植物合子后亲和性因素的理解的空白，并有助于解决染色质和生长调节剂作为剂量敏感成分的功能。尽管非整倍体，即基因组元素的不平衡剂量，与癌症有关，并导致唐氏综合症等多种遗传性疾病，但它在人类中的分子基础很难研究。植物拟南芥提供了剖析真核生物模型中剂量决定因素的机会。在这项研究中获得的知识可能有助于了解与剂量相关的疾病，并可能有助于预防和治疗这些疾病。

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.