Fixing heterosis in Canola using apomixis

利用无融合生殖修复双低油菜籽杂种优势

• 批准号: RGPIN-2022-04883
• 负责人: Sharbel, Timothy
• 金额: $ 2.04万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763592
• 关键词: Fixing; heterosis; Canola; using; apomixis

Apomixis is a naturally occurring form of asexual reproduction through seeds in plants which differs from sexual seed formation in three essential developmental events that are genetically controlled: (i) formation of a chromosomally unreduced egg cell (apomeiosis), (ii) parthenogenetic (without fertilization) embryonic development of this egg cell, and (iii) fertilization of the polar nuclei with male gametes to produce chromosomally balanced endosperm (pseudogamy)1. Together these events produce apomictic seeds with embryos that are genetic clones of the mother plant. Importantly, the development of this technology in crops would enable the permanent fixation of any heterozygous genotype, regardless of its genomic heredity and phenotypic complexity, in a single generation1. The multiple uses of apomixis in agriculture have long been recognized as important future steps for sustainability and food security, as it could (i) significantly shorten and lower risk in the costs and time required to produce new crop varieties, (ii) it would enable the fixation of complex multi-genic traits which cannot be bred using present technologies, and (iii) it would enable hybrid breeding and seed production in crops for which this does not exist (e.g. pulse crops and tubers)2. The estimated market improvement value of having apomixis introduced to rice alone would be $2.5 billion per year1. Despite its importance, apomixis has not yet been successfully introduced into crops, although it is under intense study in the global research community (e.g. Gates Foundation, Max Planck Society, etc.) as well as in industry. The long-term goal of my research program is to introduce apomixis into Canola (Brassica napus), one of Canada's most important crops. In this light, my lab studies the genus Boechera, a wild relative of Canola, and we have recently completed sequencing of a sexual and apomictic genome to the chromosome level, and have demonstrated in an ongoing backcrossing experiment that we can transfer apomixis to a sexual plant in a single generation. Importantly, we have a core apomixis gene candidate list (see below), and thus the short-term proposed objectives of my program are: (i) screening Arabidopsis mutant lines for these candidate apomixis genes, and (ii) multiplex manipulation of these candidate apomixis genes in Canola (and other Brassica crops). Over the last 15 years, my lab has trained a significant number of international HQPs, and in the present Discovery Grant Application new HQPs will be trained to transfer our latest discoveries to Canola, which would place Canada at the forefront of global crop plant research. The impact of utilizing apomixis in breeding programs would be enormous, as the fixation of traits demonstrating heterosis in a single generation would permit the rapid development of superior crop varieties adapted to changing environmental conditions, diverse farming niches and systems, and evolving markets.

无融合生殖是植物中通过种子进行无性生殖的自然发生形式，其与有性种子形成的不同之处在于三个受遗传控制的基本发育事件：（i）形成染色体未减数的卵细胞（无减数分裂），（ii）孤雌生殖（没有受精）这个卵细胞的胚胎发育，和（iii）极核与雄配子受精，产生染色体平衡的胚乳（假配子）1。这些事件一起产生具有胚的无融合生殖种子，所述胚是母体植物的遗传克隆。重要的是，这项技术在作物中的发展将使任何杂合基因型的永久固定，无论其基因组遗传和表型的复杂性，在一个单一的世代。长期以来，无融合生殖在农业中的多种用途一直被认为是可持续性和粮食安全的重要未来步骤，因为它可以（i）显著缩短和降低生产新作物品种所需的成本和时间的风险，（ii）它将能够固定使用现有技术无法培育的复杂多基因性状，以及（iii）它将使不存在杂交育种和种子生产的作物（例如豆类作物和块茎）能够进行杂交育种和种子生产2。仅将无融合生殖引入水稻的市场改良价值估计为每年25亿美元1。尽管其重要性，但无融合生殖尚未成功引入作物，尽管全球研究界（例如盖茨基金会，马克斯普朗克学会等）正在对其进行深入研究。以及在工业中。 我的研究计划的长期目标是将无融合生殖引入加拿大最重要的作物之一油菜（甘蓝型油菜）。在这种情况下，我的实验室研究了油菜的野生亲戚Boechera属，我们最近完成了对染色体水平的有性和无融合生殖基因组的测序，并在正在进行的回交实验中证明，我们可以在一代中将无融合生殖转移到有性植物。重要的是，我们有一个核心的无融合生殖基因候选名单（见下文），因此，我的计划的短期目标是：（i）筛选这些候选无融合生殖基因的拟南芥突变株系，和（ii）在油菜（和其他芸苔属作物）这些候选无融合生殖基因的多重操作。在过去的15年里，我的实验室已经培训了大量的国际HQP，在目前的发现资助申请中，新的HQP将接受培训，将我们的最新发现转移到卡诺拉，这将使加拿大处于全球作物研究的前沿。在育种计划中利用无融合生殖的影响将是巨大的，因为在单个世代中固定表现杂种优势的性状将允许快速开发适应不断变化的环境条件、多样化的农业生态位和系统以及不断变化的市场的上级作物品种。