EAGER: A mechanism for xylem embolism repair under tension

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In plants, hydraulic failure in the water transport system, the xylem, is caused by the introduction of gas bubbles and formation of embolisms in individual conducting cells. The fact that plants can repair xylem embolisms even when their hydraulic systems are under considerable tension has remained one of plant science's most puzzling and important mysteries - the mechanisms underlying this repair are essentially unknown despite evidence the phenomenon occurs in a wide variety of plant species. This research will test a novel hypothesis about a physical mechanism of embolism repair under tension. The research will be conducted with shrub species from field sites across North America. Measurements to be conducted include the percent loss of conductance due to embolism formation, gas contents in root and stem xylem in the field and under controlled conditions in the lab, as well as dye-tracer and anatomical studies to determine the pathways of water movement during embolism formation and repair. The research could potentially be transformative for plant biology by establishing mechanisms by which plants sustain water transport under high tension in the presence of abundant gas in their water transport cells. The proposed activity will help to fund a Ph.D. student and a postdoctoral position. At Cal State Fullerton, the project will include active involvement of undergraduate students in the research, including a large number of students from underrepresented groups. The research potentially will have implications for application in horticulture and agriculture, most directly for sustainable irrigation management practices of woody fruit crops.