Genomics and biology of sex determination in poplars, willows and relatives (Salicaceae)

杨树、柳树及其近缘植物（杨柳科）性别决定的基因组学和生物学

• 批准号: RGPIN-2014-05820
• 负责人: Cronk, Quentin
• 金额: $ 2.91万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611864
• 关键词: Genomics; biology; sex; determination; poplars

The origin of separate sexes in plants from hermaphrodite ancestors is a major problem in biology. Plants with unisexual individuals (dioecy) are relatively rare compared to hermaphrodites and there are as yet comparatively few examples with fully sequenced genomes. Much of the previous work on this problem has been carried out on Silene (campion) which does not yet have a fully sequenced genome. Recent work in my laboratory (Hefer, Geraldes et al., in prep.) and in collaboration with others at UBC, has located the gender-determining region of the genome of poplar (Populus trichocarpa), a dioecious tree with excellent genomic resources. This project will fully characterize the sex-determining region in poplar in order to determine the basis of gender differentiation in these trees. We will also determine whether or not willow uses the same system. Current theory suggests that a gender-determining region on a chromosome should quickly expand (over a few million years) to form a non-pairing sex chromosome. Paradoxically, although the poplar gender-determining region appears to be old it is still small, occupying only a small part of its chromosome, which still pairs along most of its length. This research program seeks to discover the reason for the limited expansion of the sex-determining region by analyzing the evolutionary dynamics of sex-linked sequences across numerous poplar species. Willows and poplars (Salicaceae) form an ecologically and economically important component of the Canadian landscape, from the boreal to mountains and prairie. Poplars are grown for timber and pulp, as biomass crops and for farm windbreaks. Willows are increasingly grown as short rotation biomass crops and for environmental stabilization (slopes, riverbanks) and phytoremediation. Dioecy is an important aspect of the biology of these plants, and the division of sexes affects their ecology, evolution, growth physiology and commercial breeding. We have begun to develop genetic assays which in validation tests can correctly determine gender using the presence or absence of gender-specific markers. This opens numerous avenues of scientific exploration. An example is sex-ratio determination. There are theoretical reasons why sex-ratios of 1:1 should be the norm. However in numerous willows and some poplars significant deviations have been recorded (usually F2:1M) based on counts of reproductive individuals. We will use novel gender-assay tools to determine at what stage of the life-cycle these deviations are established, whether at pollen, embryo, seedling or adult stage. Knowing the life-cycle stage at which gender ratios are established is the first step towards allowing us to establish a mechanism. Furthermore this research will allow us to generate new insights into gene flow and population genetics of these important Canadian landscape plants. The non-recombining, uniparentally inherited sex chromosome provides a highly suitable genetic marker for species identification ("barcoding"), tree ancestry determination and hybridization dynamics. It could be used, for example to help establish whether, and to what extent, planted exotic poplars may be hybridizing with native poplars. An important practical outcome of this work will be the development of reliable gender assays for all economically and ecologically important N. American Salicaceae species as a community resource. Rapid and accurate identification of gender in Populus and Salix has many uses. For instance it will permit accelerated selection of material for breeding and allow accurate determination of sex-ratio and sex distribution in wild populations.

从雌雄同体的祖先开始，植物的两性分离是生物学中的一个主要问题。与雌雄同体相比，具有单性个体（雌雄异株）的植物相对罕见，并且迄今为止具有完全测序的基因组的例子相对较少。关于这个问题的许多先前的工作已经在Silene（坎皮翁）上进行，其还没有完全测序的基因组。我实验室最近的工作（Hefer，Geraldes等人，（正在编写中）与不列颠哥伦比亚大学的其他人合作，已经定位了杨树基因组的性别决定区域，杨树是一种雌雄异株的树木，拥有极好的基因组资源。 本项目将充分描述杨树性别决定区的特征，以确定这些树木性别分化的基础。我们还将确定杨柳是否使用相同的系统。目前的理论认为，染色体上的性别决定区域应该迅速扩大（超过几百万年），形成一个非配对的性染色体。奇怪的是，虽然杨树的性别决定区看起来很老，但它仍然很小，只占据了染色体的一小部分，染色体仍然沿着沿着的大部分长度配对。这项研究计划旨在通过分析众多杨树物种的性连锁序列的进化动态来发现性别决定区有限扩张的原因。 柳树和杨树（杨柳科）形成了加拿大景观的生态和经济重要组成部分，从北方到山区和草原。杨树被种植用于木材和纸浆，作为生物质作物和农场防风林。柳树越来越多地作为短期轮作的生物质作物种植，并用于环境稳定（斜坡、河岸）和植物修复。雌雄异株是这些植物生物学的一个重要方面，性别的划分影响着它们的生态、进化、生长生理和商业育种。我们已经开始开发基因检测，在验证测试中可以使用性别特异性标记的存在或不存在正确地确定性别。这为科学探索开辟了许多途径。 一个例子是性别比例的确定。有理论上的理由说明为什么1：1的性别比例应该是正常的。然而，在许多柳树和一些杨树显着的偏差已记录（通常F2：1M）的基础上计数的生殖个体。我们将使用新的性别测定工具，以确定在生命周期的哪个阶段，这些偏差是建立在花粉，胚胎，幼苗或成人阶段。了解确定性别比例的生命周期阶段是使我们能够建立一种机制的第一步。此外，这项研究将使我们能够对这些重要的加拿大园林植物的基因流动和种群遗传学产生新的见解。非重组、单亲遗传的性染色体为物种鉴定（"条形码"）、树木祖先确定和杂交动力学提供了非常合适的遗传标记。例如，它可以用来帮助确定是否以及在多大程度上，种植的外来杨树可能与本地杨树杂交。 这项工作的一个重要的实际成果将是为所有经济和生态上重要的N。美国杨柳科植物作为一种群落资源。杨柳属植物性别的快速准确鉴定具有重要的应用价值。例如，它将允许加速育种材料的选择，并允许准确确定野生种群的性别比例和性别分布。