CAREER: Water movement in leaves and roots of C3 and C4 grasses: mechanisms, coordination and impact on whole plant growth during soil and atmospheric drought

植物科学面临的两个主要挑战是了解干旱期间导致植物生长下降的机制，并查明使某些植物比其他植物更抗旱的性状。识别这些性状可以帮助作物育种者开发耐旱作物。草类占据了大约40%的陆地表面，包括一些最重要的作物，如谷物和饲草，需要针对这些挑战进行研究。草类尤其有趣，因为它们在光合作用机制上表现出独特的多样性，而这种多样性与土壤和大气干旱期间植物水分运动的差异之间的关系尚不清楚。本研究的目的是揭示导致光合多样性作物草在干旱期间生长下降的具体机制以及它们如何在重新浇水后恢复。本研究将利用先进的成像技术、新的生理方法和模型，研究不同禾本科植物在土壤和大气干旱条件下的根和叶响应。该项目将整合一项研究和教育计划，该计划将在东洛杉矶一所为少数族裔服务的本科院校开展。东洛杉矶是美国少数族裔最集中的地区之一。贯穿本科课程的研究型模块将使240名学生/年接触到植物科学的实验设计和批判性思维。由本科生领导的外展活动将有助于激励东洛杉矶缺乏服务的学校的学生接受高等教育和植物科学。本项目旨在严格测试C3和C4草在土壤和大气干旱及随后恢复期间叶片和根系水导协调的机制。研究的主要目标有三个：(1)确定脱水过程中叶片和根系水力下降与气孔导度的协调关系，以及导致叶片和根系水力下降的潜在机制；(2)定量测定水稻突变体脱水和复水过程中草脉解剖生化对叶片和根系水力导度的影响；(3)对土壤和大气干旱对叶片和根系水导度的影响及其对植物生长的影响有了新的综合认识。为了实现这些目标，我们将在不同土壤和大气干旱条件下，对12种不同的C3和C4禾本科植物，以及11种水稻水通道蛋白和静脉突变体及其野生型进行大量的生理和解剖特性研究，包括叶片和根系水力学、气体交换和尖端成像技术。使用空间明确和整个植物模型的模拟将用于测试特定假设背后的因果关系。这项工作将创造新的概念和必要的数据，以帮助改进植物生长和对气候变化的反应的预测模型。该教育计划将通过研究型讲座、课程本科研究体验和学生主导的在当地服务不足的学校开展的外展活动，帮助改变CSULA学生的经历。CSULA是一所少数民族服务机构。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。

Two major challenges in plant sciences are to understand the mechanisms leading to the decline in plant growth during drought and pinpoint traits that enable some plants to be more drought resistant than others. Identifying these traits can help inform crop breeders in the development of drought tolerant crops. Research addressing these challenges is needed for grasses, which dominate about 40% of terrestrial surfaces and include some of the most important crops, such as cereals and forage grasses. Grasses are particularly interesting as they exhibit unique diversity in their photosynthetic machinery, and it remains unclear how this diversity relates to differences in plant water movement during soil and atmospheric drought. The goal of this research is to unravel the specific mechanisms which lead photosynthetically diverse crop grasses to decline in growth during drought and how they recover upon re-watering. This work will focus on disentangling the root and leaf responses of diverse grasses during soil and atmospheric drought using cutting-edge imaging techniques, new physiological approaches and modelling. The project will integrate a plan of research and education at a minority-serving undergraduate institution in East Los Angeles— one of the largest concentrations of ethnic minority groups in the nation. Research-like modules integrated throughout the undergraduate curriculum will expose 240 students/year to experimental design and critical thinking in plant sciences. Outreach activities led by undergraduate students will help inspire students at underserved schools of East Los Angeles into higher education and plant sciences.This project seeks to rigorously test mechanisms underlying the coordination in leaf and root hydraulic conductance of C3 and C4 grasses during soil and atmospheric drought and subsequent recovery. Three specific objectives will be carried out: (1) Determine the coordination in leaf and root hydraulic decline with stomatal conductance during dehydration and the underlying mechanisms leading to their decline; (2) Quantify the effects of grass vein anatomy and biochemistry on leaf and root hydraulic conductance during dehydration and rehydration using rice mutants; (3) Achieve a new integrated understanding of the effects of soil and atmospheric drought on leaf and root hydraulic conductance and their impact on plant growth. To carry out these objectives, a large suite of physiological and anatomical traits including leaf and root hydraulics and gas exchange and cutting-edge imaging techniques will be performed on 12 diverse C3 and C4 grasses, and 11 rice aquaporin and vein mutants and their wild type growing in a greenhouse under different soil and atmospheric drought conditions. Simulations using spatially-explicit and whole plant modelling will be employed to test the causality behind specific hypotheses. This work will create new concepts and essential data to help improve predictive models of plant growth and responses to climate change. The educational plan will help transform the experience of students at CSULA, a minority serving institution, through research-infused lectures, a Course Undergraduate Research Experience and student-led outreach activities at local underserved schools.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.