EAGER: Clonal propagation of tomato through seeds

EAGER：番茄通过种子的克隆繁殖

• 批准号: 1936872
• 负责人: Venkatesan Sundaresan
• 金额: $ 29.91万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1936872&HistoricalAwards=false
• 关键词: EAGER; Clonal; propagation; tomato; through

The large-scale use of hybrid seeds over the past century has contributed to a revolution in agriculture. Hybrid crop plants produce high yields, but due to genetic segregation, their progeny have variable and frequently low yields. This means that hybrid seeds have to be generated afresh for every season, using labor-intensive methods such as hand pollination, resulting in substantially higher costs. Consequently, hybrids are underutilized for many crops, especially by farmers in developing countries. Recently a technology called synthetic apomixis has been developed to enable hybrid rice plants to produce seeds that are genetic clones of the parent plant, such that the progeny can produce the same high yields as the parent plant. The method mimics a process called apomixis that occurs naturally in many asexual plant species, and utilizes genome editing together with manipulation of gene expression to bypass both genetic segregation and fertilization. In this project, the method for clonal propagation of hybrid seeds developed for the monocot plant rice will be modified and tested for use in tomato, which is a dicot species. If successful in tomato, the method can be extended to other major crops that are dicots, such as soybean and cotton, with correspondingly large impacts on world agriculture.The first successful propagation of clonal seeds by a sexually reproducing plant has been recently achieved in rice, through the elimination of meiosis by CRISPR-Cas9 genome editing of three meiotic genes, followed by parthenogenesis arising from egg cell expression of an embryogenic transcription factor of the BABY BOOM family. The resulting seeds were clonal and maintained the genome wide heterozygosity of the parent plant. A similar approach will be used in this project on the dicot plant tomato, to enable the propagation of hybrid tomato plants clonally through seeds. Tomato orthologs of the highly conserved meiosis genes REC8, PAIR1 and OSD1 will be genome edited by CRISPR-Cas9 to eliminate meiosis and form unreduced gametes. Parthenogenesis of the unreduced egg cell will be induced by ectopic expression of candidate embryogenic factors identified by orthology to embryonic factors in rice and Arabidopsis, including those of the BABY BOOM transcription factor family. Putative clonal progeny will be identified by their chromosomal ploidy, and validated by whole genome sequencing to confirm maintenance of parental heterozygosity in their genomes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在过去的世纪里，杂交种子的大规模使用促成了农业革命。 杂交作物植物产生高产量，但由于遗传分离，它们的后代具有可变的且经常低的产量。 这意味着杂交种子必须在每个季节重新产生，使用人工授粉等劳动密集型方法，导致成本大幅增加。 因此，许多作物，特别是发展中国家的农民，对杂交种利用不足。 最近，已经开发了一种称为合成无融合生殖的技术，以使杂交水稻植物能够产生作为亲本植物的遗传克隆的种子，使得后代可以产生与亲本植物相同的高产量。 该方法模拟了在许多无性植物物种中自然发生的称为无融合生殖的过程，并利用基因组编辑和基因表达操纵来绕过遗传分离和受精。 在本项目中，将改进为单子叶植物水稻开发的杂交种子克隆繁殖方法，并测试其在双子叶植物番茄中的应用。 如果在番茄中取得成功，该方法可以扩展到其他主要双子叶作物，如大豆和棉花，对世界农业产生相应的巨大影响。最近在水稻中首次成功实现了有性繁殖植物的克隆种子繁殖，通过CRISPR-Cas9基因组编辑三个减数分裂基因消除减数分裂，随后是由BABY BOOM家族的胚胎发生转录因子的卵细胞表达引起的孤雌生殖。所得到的种子是克隆的，并且保持了亲本植物的全基因组杂合性。该项目将在双子叶植物番茄上使用类似的方法，以通过种子克隆繁殖杂交番茄植物。 高度保守的减数分裂基因REC 8、PAIR 1和OSD 1的番茄直系同源物将通过CRISPR-Cas9进行基因组编辑，以消除减数分裂并形成未减数配子。未减数卵细胞的孤雌生殖将通过候选胚胎发生因子的异位表达来诱导，所述候选胚胎发生因子通过与水稻和拟南芥中的胚胎因子的直系同源来鉴定，包括BABY BOOM转录因子家族的那些。 假定的克隆后代将通过其染色体倍性进行鉴定，并通过全基因组测序进行验证，以确认其基因组中亲本杂合性的维持。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。