Collaborative Research: Hybrid Seed Inviability and the Evolution of Endosperm Development in Mimulus

合作研究：杂交种子的不存活性和酸浆菌胚乳发育的进化

• 批准号: 1558113
• 负责人: John Willis
• 金额: $ 50.5万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558113&HistoricalAwards=false
• 关键词: Collaborative; Research; Hybrid; Seed; Inviability

The seed of flowering plants contains two very important structures: the embryo that will become a seedling and eventually grow into the mature plant, and the endosperm, a tissue that provides nutrients to the embryo as it grows. If you have eaten rice, you have eaten endosperm, the starchy portion that fills the majority of the rice grain. Since the emergence of agriculture, humans have selected and bred seeds with a larger and starchier endosperm portion, ultimately creating the crop varieties we now depend upon. Endosperm, either directly or indirectly through animal feed, now provides an estimated 67% of the calories consumed by humans worldwide, and improving on these varieties remains of fundamental importance. Thus, from both an agricultural and food security perspective the development of the endosperm is critical to humankind's survival. This research will investigate the genes that control endosperm development and the molecular and evolutionary interactions between the endosperm and the embryo in the monkey flower (genus Mimulus). Although not eaten by humans, due to its ecological and evolutionary history, Mimulus provides a unique opportunity to study evolutionary and molecular aspects of the interactions between endosperm and embryo. As these interactions regulate the growth of the endosperm and thus the size of the nutritious portion of the seed in agricultural varieties, the results of this research in Mimulus are expected to engender a molecular understanding of a developmental process critical to human agricultural productivity. This research will inspire new high school biology teaching modules in genetics, evolution, and plant developmental biology that highlight the importance of the endosperm to humankind's diet, as well as the roles of pollinators and reproductive barriers in generating the diversity of life through the evolutionary process.Recent evidence links the evolutionary theory of parent-offspring conflict over maternal resources to the evolution of epigenetically imprinted genes controlling normal seed endosperm development. In interploidy hybrids, dosage-sensitivity of paternal and maternal allelic expression in developing endosperm is critical to normal development, and disruption leads to seed abortion. As yet it remains unknown whether such conflict over embryo provisioning leads to evolutionary divergence of imprinted genes or their targets, and ultimately hybrid seed lethality, in diploid species. The investigators propose to test this possibility by determining the genetic basis and evolutionary mechanisms underlying species divergence in endosperm development and leading to hybrid seed abortion, a principal isolating barrier in the Mimulus guttatus sp. complex. This research integrates genomic, molecular genetic and developmental biology approaches, utilizing high-throughput genome mapping, RNA sequencing technologies, and transgenic techniques to elucidate the genetic mechanisms contributing to seed abortion in M. guttatus x M. nudatus crosses. In so doing, it examines questions of fundamental interest to evolutionary biologists (how are new species formed?), and to developmental biologists (how is endosperm growth regulated?) while addressing a question of interest to both: what molecular changes might rapidly evolve when the mother's need to regulate growth and development differs from that of her offspring? Answering these questions will shed light on the developmental processes regulating endosperm growth and the evolutionary mechanisms driving divergence in flowering plants.

开花植物的种子包含两个非常重要的结构：胚胎和胚乳，胚胎将成为幼苗并最终长成成熟植物，胚乳是在胚胎生长时为胚胎提供营养的组织。如果您吃过米饭，那么您就吃过胚乳，即填充米粒大部分的淀粉部分。自从农业出现以来，人类就选择并培育了胚乳部分更大、淀粉含量更高的种子，最终创造了我们现在依赖的农作物品种。目前，胚乳直接或间接通过动物饲料提供了全世界人类消耗热量的 67%，因此改进这些品种仍然至关重要。因此，从农业和粮食安全的角度来看，胚乳的发育对人类的生存至关重要。 这项研究将研究控制猴花（拟酸浆属）胚乳发育的基因以及胚乳和胚胎之间的分子和进化相互作用。尽管不被人类食用，但由于其生态和进化历史，酸浆菌为研究胚乳和胚胎之间相互作用的进化和分子方面提供了独特的机会。 由于这些相互作用调节了农业品种中胚乳的生长，从而调节了种子营养部分的大小，因此这项在含酸浆中的研究结果预计将产生对人类农业生产力至关重要的发育过程的分子理解。这项研究将激发遗传学、进化论和植物发育生物学方面的新的高中生物教学模块，这些模块强调胚乳对人类饮食的重要性，以及传粉媒介和生殖障碍在进化过程中产生生命多样性的作用。最近的证据将亲子冲突的进化理论与控制表观遗传印记基因的进化联系起来。 种子胚乳发育正常。在倍体间杂种中，发育中的胚乳中父本和母本等位基因表达的剂量敏感性对于正常发育至关重要，破坏会导致种子败育。迄今为止，尚不清楚这种关于胚胎供应的冲突是否会导致二倍体物种中印记基因或其目标的进化分歧，并最终导致杂交种子的致死率。研究人员建议通过确定胚乳发育中物种分化的遗传基础和进化机制以及导致杂种种子败育（Mimulus guttatus sp. 的主要隔离障碍）来测试这种可能性。复杂的。这项研究整合了基因组学、分子遗传学和发育生物学方法，利用高通量基因组作图、RNA测序技术和转基因技术来阐明导致M. guttatus x M. nuudatus杂交种子败育的遗传机制。在此过程中，它研究了进化生物学家（新物种是如何形成的？）和发育生物学家（胚乳生长是如何调节的？）根本感兴趣的问题，同时解决了双方都感兴趣的问题：当母亲调节生长和发育的需要与其后代不同时，哪些分子变化可能会迅速进化？ 回答这些问题将有助于揭示调节胚乳生长的发育过程以及驱动开花植物分化的进化机制。