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

植物科学中的两大挑战是了解干旱期间导致植物生长下降的机制，并准确定位使某些植物比其他植物更具抗旱性的性状。识别这些特征有助于作物育种者在开发耐旱作物方面提供信息。应对这些挑战的研究对于草来说是必要的，它占据了约40%的陆地表面，包括一些最重要的作物，如谷物和牧草。草尤其令人感兴趣，因为它们在光合作用机制中表现出独特的多样性，目前尚不清楚这种多样性与土壤和大气干旱期间植物水分运动的差异有何关系。这项研究的目标是揭示导致光合作用多样的作物草在干旱期间生长下降的具体机制，以及它们在重新浇水后如何恢复。这项工作将集中于利用尖端成像技术、新的生理学方法和模型来解开不同牧草在土壤和大气干旱期间的根和叶的反应。该项目将整合东洛杉矶一所为少数族裔服务的本科生机构的研究和教育计划。东洛杉矶是美国少数族裔群体最集中的地区之一。在整个本科课程中整合的类似研究的模块将使240名学生/年接触植物科学中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服务不足的东洛杉矶学校的学生接受高等教育和植物科学。该项目旨在严格测试C3和C4草在土壤和大气干旱以及随后的恢复过程中叶和根的水力传导性协调的潜在机制。将实施三个具体目标：(1)确定脱水过程中叶片和根的水力下降与气孔导度的协调及其导致它们下降的潜在机制；(2)利用水稻突变体量化草脉解剖和生物化学对叶和根脱水和复水期间叶和根的水力导度的影响；(3)对土壤和大气干旱对叶和根的水力导度的影响及其对植物生长的影响有一个新的综合理解。为了实现这些目标，将对12种不同的C3和C4草以及11种水稻水孔蛋白和叶脉突变体及其野生型在不同土壤和大气干旱条件下生长在温室中进行一系列生理和解剖学特性的研究，包括叶和根的水力、气体交换和尖端成像技术。使用空间显式和全植物模型的模拟将被用来检验特定假设背后的因果关系。这项工作将创造新的概念和基本数据，以帮助改进植物生长和对气候变化的反应的预测模型。该教育计划将通过融入研究的讲座、本科生研究体验课程以及学生在当地服务不足的学校开展的外展活动，帮助转变CSULA这一少数族裔服务机构的学生的经历。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.