18-BTT:Harnessing the power of cellular memory to enhance the breeding potential of crops

培育出具有重要商业价值的作物品种，如玉米、南瓜和棉花，极大地提高了作物产量以及对杀虫剂和除草剂的抗性。虽然这些菌株是维持快速增长的全球人口的理想选择，但将同质性和生产力置于可靠和多样化的粮食生产之上，导致了基因变异的严重损失。将遗传变异重新引入农业上重要的品系的传统方法包括与野生近缘杂交，野生近缘拥有比作物品系更多的遗传多样性。然而，与野生近亲回交往往会导致额外性状的导入，从而降低产量。或者，也有可能利用作物基因组中已经存在的隐藏的遗传多样性，这些遗传多样性通常被DNA甲基化等抑制性修饰在转录上沉默。在全基因组范围内消除DNA甲基化会导致通常沉默的基因座的可遗传激活，导致新基因表达模式的表型改变。在模式植物物种中创建去甲基化品系导致了表型多样性的增加，这表明新的、未开发的变异来源可以在不进行基因修改的情况下被解锁。因此，在玉米等物种中创建去甲基化品系将有助于通过解锁隐蔽变异、促进对生长带变化的耐受性和对毒力病原体的出现来促进作物改良。在这项建议中，我们的目标是利用我们最近发现的在再生过程中诱导去甲基化的优势来创建去甲基化玉米品系。这项提议有两个主要目标。首先，通过体细胞胚胎发生，检测不同组织直接再生植株对玉米沉默基因的诱导去甲基化和激活的效果。第二个目标是探索将应激处理与体细胞胚胎再生结合起来是否会导致表观遗传印记，从而增强应激反应。我们将结合我们的直接再生和表观基因组学的专业知识来评估这种新方法的可行性，并设计独立于遗传变化的植物基因组。在玉米中成功实施这种方法的能力将迅速提高创造理想表型的能力，并将促进植物生物技术的发展。

The creation of strains of commercially important crops such as maize, squash, and cotton has resulted in vastly increased crop yields as well as resistance to pesticides and herbicides. While these strains are ideal for sustaining a rapidly expanding global population, the prioritization of homogeneity and productivity over reliable and diversified food production has resulted in a severe loss of genetic variation. Traditional approaches for reintroducing genetic variation into agriculturally important strains involve crossbreeding with wild relatives, which possess more genetic diversity than crop strains. However, backcrossing with wild relatives often results in the introgression of additional traits which lower yield.Alternatively, it may be possible to harness hidden genetic diversity already present in crop genomes which is normally transcriptionally silenced by repressive modifications such as DNA methylation. Removing DNA methylation at a genome-wide scale results in the heritable activation of loci normally silenced, leading to altered phenotypes from novel gene expression patterns. The creation of demethylated lines in model plant species has resulted in increased phenotypic diversity indicating that new, untapped source of variation that can be unlocked without genetic modification. Therefore, the creation of demethylated lines in species such as maize would serve to facilitate crop improvement by unlocking cryptic variation, promoting tolerance to changes in growth zones and the emergence of virulent pathogens. In this proposal we aim to create demethylated maize lines by taking advantage of our recent discovery that demethylation is induced during regeneration. There are two major goals of this proposal. The first, is to test the efficacy of induced demethylation and activation of silenced genes in maize as a result of direct plant regeneration from different tissues through somatic embryogenesis. The second goal, is to explore if coupling stress treatments with regeneration from somatic embryos could leads to epigenetic imprints that could enhance stress responses. We will combine our expertise of direct regeneration and epigenomics to assess the feasibility of this novel approach and to engineer plant genomes independent of genetic changes. The ability to successfully implement this method in maize will rapidly advance the ability to create desirable phenotypes and will advance plant biotechnology.