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The hydraulic legacy of C4 evolution in the grasses: Phylogenetic, physiological and genetic controls on water transport

草类中 C4 进化的水力遗产：水运输的系统发育、生理和遗传控制

基本信息

批准号：
1856587
负责人：
Brent Helliker
金额：
$ 85.86万
依托单位：
University of Pennsylvania
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-05-15 至 2024-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1856587&HistoricalAwards=false
关键词：
hydraulic legacy C4 evolution grasses

项目摘要

Grasslands, savannas and croplands cover about 40% of the terrestrial biosphere and grasses represent all major grain crops, yet little is known about how anatomy affects water movement through grasses. The evolution and expansion of grassland biomes 20-30 million years ago was due to an increase in aridity; therefore, grass evolution, physiology and ecology are inextricably linked to the acquisition, use and movement of water. Research into the evolution of the C4 photosynthetic pathway from the C3 photosynthetic pathway has forged collaborations across evolutionary biologists, physiologists, paleo-ecologists and plant geneticists who are attempting to engineer C4 photosynthesis into rice, yet comparatively little of this research has been focused on the hydraulic side of C4 evolution. The aim of this research is for a better understanding of how grass leaf anatomy, in concert with the evolution of C4 photosynthesis, controls water transport through a leaf. This research will provide a better physiological, theoretical and genetic understanding of hydraulic controls and limits in grasses. Targets for improving crop performance will be identified, while adding insight into the importance of leaf hydraulics in the evolution of C4 photosynthesis. Additionally, new research-related teaching modules will be developed for the University of Pennsylvania's Biology Professional Development Program. The program increases the biology knowledge of high school teachers in the Philadelphia School district, a heavily-underfunded school system. This project will also train a postdoc, a graduate student, and several undergraduates.C4 grasses evolved from C3 grasses more than 20 times independently over tens of millions of years within the PACMAD clade of grasses. By allowing phylogeny to guide the examination of function, and using a combination of theory and experimentation, the following hypotheses will be addressed in this project: 1. The primary selective pressures for the evolution of C4 changed (e.g. CO2 vs. water availability) depending on when C4 evolved within a lineage, the effects of which are still measurable today. 2. Upon the evolution of C4 within a grass lineage, there was selection for hydraulic reorganization within the leaf, notably a decrease in leaf hydraulic conductance with no decrease in vein density. 3. By examining hydraulic and anatomical differences within a phylogenetic context, insight can be gained on the controls of water flux in the within-xylem (liquid water) and outside-xylem (both liquid and vapor) components of the flux pathway in relation to photosynthetic variation. 4. Genome-level mapping of recombinant inbred lines of a Setaria viridis x S. italica cross will (i) give mechanistic insight into how changes in hydraulic architecture affect water flux through leaves, and (ii) identify targets for crop improvement. An integrative approach using physiological measurements of hydraulic conductance in concert with leaf-water enrichment of heavy stable isotopes will be used in an iterative fashion with fine-scale, physical modeling of water flux through leaves to determine the anatomical controls on leaf hydraulics.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.

草地、稀树草原和农田覆盖了大约40%的陆地生物圈，草代表了所有主要的粮食作物，但人们对解剖学如何影响草中的水分运动知之甚少。2000 - 3000万年前草原生物群落的进化和扩张是由于干旱的增加;因此，草的进化，生理学和生态学与水的获取，使用和运动有着不可分割的联系。从C3光合途径进化到C4光合途径的研究已经在进化生物学家，生理学家，古生态学家和植物遗传学家之间建立了合作，他们试图将C4光合作用工程化到水稻中，但相对较少的研究集中在C4进化的水力方面。本研究的目的是为了更好地了解草叶解剖学如何与C4光合作用的进化相一致，控制水分通过叶子的运输。这项研究将提供一个更好的生理，理论和遗传的理解液压控制和限制在草。将确定提高作物性能的目标，同时增加对C4光合作用进化中叶片水力学重要性的认识。此外，将为宾夕法尼亚大学的生物专业发展计划开发新的研究相关教学模块。该计划增加了费城学区高中教师的生物学知识，费城学区是一个资金严重不足的学校系统。该项目还将培养一名博士后、一名研究生和几名本科生。在PACMAD进化枝中，C4草在数千万年的时间里独立地从C3草进化了20多次。通过允许遗传学来指导功能的检查，并使用理论和实验的结合，以下假设将在这个项目中得到解决：1。C4进化的主要选择压力（例如CO2与水的可用性）取决于C4在谱系内进化的时间，其影响今天仍然可以测量。2.在进化的C4内的草谱系，有选择的叶片内的水力重组，显着降低叶片水力传导度没有减少静脉密度。3.通过研究系统发育背景下的水力和解剖学差异，可以获得洞察力的控制内木质部（液态水）和外木质部（液体和蒸汽）的通量路径的组件在光合变化的水通量。4.狗尾草×狗尾草重组自交系的基因组定位。italica cross将（i）提供水力结构变化如何影响通过叶片的水通量的机理见解，以及（ii）确定作物改良的目标。将采用一种综合方法，利用水力传导的生理测量与叶水富集重稳定同位素，通过叶片的水通量的物理模型，以确定叶片水力学的解剖控制。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查评估的支持的搜索.