COLLABORATIVE RESEARCH: Evolution of genetic networks in grass abscission zones

农业依赖于植物在收获之前保持种子，然而野生植物需要在一个被称为碎裂或脱落的过程中掉落种子。因此，小麦、水稻和玉米等谷类作物的驯化是人类选择自发突变植物的结果，这些植物不会破碎。在面临人口快速增长和气候变化的世界中，了解粉碎机制至关重要，以便能够驯化和改进新的野生或较少驯化的谷类作物，从而使食物选择多样化并改善边缘环境中的农业。该项目将研究破碎过程，该过程由一组称为脱落区（AZ）的专门细胞控制。将比较AZ在不同谷类作物及其野生近缘种中的细胞发育情况，包括珍珠粟和高粱这两种具有经济价值和耐旱性的谷物。该项目旨在鉴定功能性AZ所需的基因，并了解这些基因的修饰如何导致不同物种AZ的形态差异。高中生，本科生和中学教师将参与进行研究。为中学教师提供的研究经验将用于制定新的课程计划，并进一步影响下一代的科学教育。基因调控网络在进化过程中不断被修改，但修改的速度和变化的性质通常是未知的。该项目解决了控制植物脱落区（AZ）网络变化的速度和模式，这是一个特殊的细胞层，允许植物掉落种子、果实、花瓣或叶子。三种远亲的禾草物种（杂草稻、短茅草和尾草）的AZ由不同的基因控制，表明潜在的遗传网络重新连接。本项目将调查禾本科禾本科亚科其他物种的AZ网络，包括野生和栽培珍珠粟（Cenchrus americanus，与狗尾草属密切相关）和高粱（sorghum bicolor），这是一个更遥远的亲戚。组织学（使用光学和透射电子显微镜）和基因表达模式（RNA-seq）将在发育的几个阶段进行表征。为了确定广泛的重连接是否来自顺式调控模块的变化，我们将结合突变体分析、RNA-seq、ap -seq和生物信息学，对遗传易感物种尾草属（Setaria）和短尾草属（Brachypodium）中两个保守转录因子YAB2/SH1和MYB26的上下游调控因子进行表征。为了确定不同的早期调控网络是否集中于保守的晚期遗传相互作用，将在分离前后评估转录组学、酶学和细胞壁的变化。总之，这些数据将决定调节AZ形成的基因网络如何以及以多快的速度随着时间的推移而重塑。高中学生和教师将参与植物表型的许多方面。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Agriculture depends on plants that hold on to their seeds until harvest, yet wild plants need to drop their seeds, in a process known as shattering or abscission. Therefore, domestication in cereal crops such as wheat, rice, and corn was the result of human selection for spontaneous mutant plants that did not shatter. In a world facing rapid population growth and changing climates, it is crucial to understand the mechanism of shattering to be able to domesticate and improve new wild or less domesticated cereal crops, thereby diversifying food choices and improving agriculture in marginal environments. This project will examine the shattering process, which is controlled by a specialized set of cells known as an abscission zone (AZ). Cell development of the AZ will be compared in different cereal crops and their wild relatives, including pearl millet and sorghum, two economically valuable and drought tolerant cereals. The project aims to identify genes that are required for a functional AZ, and to understand how modification of these genes causes morphological differences in the AZ in different species. High school students, undergraduates and secondary school teachers will be involved in conducting the research. The research experience provided to secondary school teachers will be used to develop new lesson plans, and further impact next generation education in science. Gene regulatory networks are continually modified over evolutionary time, but the speed of modification and the nature of the changes are generally not known. This project addresses both the tempo and mode of change in the network controlling the abscission zone (AZ) in plants, a specialized cell layer that permits plants to drop seeds, fruits, petals or leaves. The AZ of three distantly related grass species (weedy rice, Brachypodium, and Setaria) is controlled by distinct sets of genes, suggesting rewiring of the underlying genetic network. This project will investigate the AZ networks among additional species in grass subfamily Panicoideae, including wild and cultivated pearl millet (Cenchrus americanus, closely related to Setaria) and sorghum (Sorghum bicolor), a more distant relative. Histology (using light and transmission electron microscopy) and gene expression patterns (RNA-seq) will be characterized at several stages of development. To determine whether the extensive rewiring comes from changes in cis-regulatory modules, the upstream and downstream regulators of two conserved transcription factors, YAB2/SH1 and MYB26, will be characterized in the genetically tractable species Setaria and Brachypodium, with a combination of mutant analysis, RNA-seq, DAP-seq and bioinformatics. To determine if the disparate early regulatory networks converge on a conserved late stage set of genetic interactions, transcriptomic, enzymatic, and cell wall changes will be evaluated right before and after abscission. Together, these data will determine how and how fast the gene network regulating AZ formation is remodeled over time. High school students and teachers will be involved in many aspects of plant phenotyping.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.