Functional and Genetic Basis of Leaf Venation: Testing and Expanding Theory and Core Knowledge with Arabidopsis Vein Mutants and Ecotypes

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Leaf vein traits are considered to be critical for understanding plant adaptation to the environment, responses to environmental changes, and crop performance. However, the direct linkages of vein traits to whole plant performance are not completely understood. This project will test and extend current theory for the role of leaf veins in plant function, using the model species Arabidopsis thaliana. The project will determine the genes underlying different vein traits and how these lead to higher-level functions including water transport and growth. This work will result in discoveries of how genes determine plant function, create resources for improving plant productivity, and clarify the evolution of natural species, with critical impacts in the fields of plant physiology, ecology and genetics. Numerous undergraduate students will be integrated into the project, receiving training is scientific methodology and data analysis. The project includes the creation of a new web resource to enable K-12 students, teachers, and members of the public to conduct their own analyses to estimate how vein properties affect plant function. The work aims to advance national prosperity and welfare through applications in agriculture and ecological sustainability and education of science students and the public in plant biology. Leaf venation is increasingly recognized as important to plant performance, with applications from agriculture to paleobiology. This understanding is based on comparative studies across diverse plant species, which showed that major structural features of leaf venation influenced leaf gas exchange. However, the theory for the importance of vein traits has not yet been tested rigorously in a model system, such as A. thaliana. Vein mutants have been identified with leaf phenotypes showing altered vein cross-sectional anatomy, spacing, patterning and/or connectivity. The project will utilize both leaf vein mutants and natural ecotypes previously subjected to genomic sequencing in a combination of physiological experiments, modeling, and genetic analyses. Hypothesized mechanistic trait linkages and genome-wide association of traits will be measured to address two research questions: (1) How do leaf vein traits influence hydraulics, gas exchange and growth? (2) What are the genetic loci associated with leaf vein traits, and how do they determine higher-level function across A. thaliana genotypes? The project breaks new ground in the ability to model how gene sequence determines key plant traits that scale up to whole plant function. The integrative approach will provide new insights into plant physiology and genetic architecture and set the stage for numerous further analyses at the intersection of these fields. Broader Impacts work will capitalize on the great appeal of leaf venation for scientists, students and laypeople. In collaboration with undergraduate students and under-represented high school students, a crowd-sourcing website will be created, "VenationNation", to provide unique resources for researchers, citizens and students to become involved in leaf venation research. The site will contain downloadable images of leaf vein systems and protocols to calculate and interpret vein traits with self-teaching and course curricula. This site will increase the involvement of citizens and students in science, provide resources for teaching, create pathways toward understanding of principles of plant science, and aid in the global dissemination of the research.