Genome editing of PHS-associated AGO4_9 genes in small grain cereals

收获前发芽（PHS）是谷物在收获前在炎热和潮湿的条件下发芽。PHS大大降低了收获谷物的经济价值，PHS每年给全球小麦产业带来的成本超过10亿美元。最近，仅在加拿大就记录了1亿美元的损失。因此，对PHS的抗性是公共部门和Corteva Agriscience等行业的小麦育种计划中非常理想的遗传性状。我们最近发现了一个关键基因，它可以作为一个开关，决定一种特定的植物如何对高湿度和过多的降雨做出反应，要么发芽早（PHS），要么不发芽（http：//www.mcgill.ca/channels/news/mcgill-discovery-should-save-wheat-farmers-millions-231037）。这种开关已经在“RNA依赖性DNA甲基化”途径中发现（Singh等人，2013年）。我们发现Argonaut基因AGO4_9类与大麦和小麦中的收获前发芽（PHS）相关（Singh和Singh，2012; Singh等人，2013年）。RNA介导的DNA甲基化（RdDM）途径的关键基因（AGO 4）与禾谷类种子休眠的相关性研究表明，AGO 4能促进DNA甲基化，是种子休眠的负调控因子。这项研究为植物科学家开辟了一个全新的探索领域，因为他们正在努力提高谷物产量，并尽量减少由于过度潮湿条件造成的损失。目前的项目提案旨在进一步了解AGO4_9在大麦和小麦种子萌发、休眠和PHS中的作用，并评估其通过基于CRISPR的基因组编辑（GE）工具开发新型PHS抗性育种系的潜力。

Pre-Harvest Sprouting (PHS) is the germination of grains before harvest under hot and humid conditions. PHS greatly diminishes the economic value of the harvested grains and the annual cost of PHS globally to the wheat industry exceeds $1 billion. Recently, a loss of $100 million has been documented in Canada alone. Therefore, resistance to PHS is a highly desirable genetic trait for the wheat breeding programs in both the public sector and industry such as Corteva Agriscience. We recently discovered a key gene that acts as a switch to determine how a particular plant will respond to high humidity and excess rainfall by either germinating early (PHS) or not (http://www.mcgill.ca/channels/news/mcgill-discovery-should-save-wheat-farmers-millions-231037). This switch has been found in in the "RNA dependent DNA Methylation" pathway (Singh et al., 2013). We found that Argonaut genes, AGO4_9 class have been associated with pre-harvesting sprouting (PHS) in barley and wheat (Singh and Singh, 2012; Singh et al., 2013). The association of key gene (AGO4) of RNA-directed DNA methylation (RdDM) pathway with PHS in cereals indicating that AGO4 enhances DNA methylation and acts as a negative regulator of seed dormancy. This piece of research opens up a completely new area of exploration for plant scientists as they are endeavoring to increase the yields of cereals and minimize losses due to excessively humid conditions. The current project proposal aims to further understand the role of AGO4_9 in seed germination, dormancy and PHS in barley and wheat and assess their potential to develop novel PHS resistant breeding lines through CRISPR-based Genome Editing (GE) tools.