Presentation Title

Water and Carbon Starvation Predisposes a Keystone Chaparral Shrub to Fungal Infection

Start Date

November 2016

End Date

November 2016

Location

Surge 171

Type of Presentation

Oral Talk

Abstract

Malosma laurina, a keystone chaparral species in the Santa Monica Mountains, has recently been experiencing dieback due to the fungal pathogen Botryosphaeria dothidea. The ongoing drought in California has greatly influenced the susceptibility of M. laurina to fungal infection. The present study seeks to understand whether carbon starvation or limited water availability increases M. laurina’s susceptibility to B. dothidea invasion. We hypothesized that B. dothidea will be able to invade water-starved plants more effectively then carbon-starved plants, thus negatively impacting photosynthesis and stomatal conductance. A controlled experiment using juvenile potted M. laurina was used to replicate irrigated and drought conditions in order to test the effects of water starvation and carbon starvation. Photosynthesis, stomatal conductance, water potential, and fungal growth along the stem was monitored throughout the experiment. We found that while carbon starvation resulted in an increased degree of infection, relative to the control, water limitation resulted in the largest degree of fungal infection. Thus, B. dothidea invaded drought-stressed xylem of potted plants more easily then irrigated plants. If the current drought persists, there will continue to be increased dieback in stands of M. laurina, which could have severe implications on the ecological stability of the Santa Monica Mountains and could increase fuel loads for fires with increased stands of dead plants.

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Nov 12th, 3:15 PM Nov 12th, 3:30 PM

Water and Carbon Starvation Predisposes a Keystone Chaparral Shrub to Fungal Infection

Surge 171

Malosma laurina, a keystone chaparral species in the Santa Monica Mountains, has recently been experiencing dieback due to the fungal pathogen Botryosphaeria dothidea. The ongoing drought in California has greatly influenced the susceptibility of M. laurina to fungal infection. The present study seeks to understand whether carbon starvation or limited water availability increases M. laurina’s susceptibility to B. dothidea invasion. We hypothesized that B. dothidea will be able to invade water-starved plants more effectively then carbon-starved plants, thus negatively impacting photosynthesis and stomatal conductance. A controlled experiment using juvenile potted M. laurina was used to replicate irrigated and drought conditions in order to test the effects of water starvation and carbon starvation. Photosynthesis, stomatal conductance, water potential, and fungal growth along the stem was monitored throughout the experiment. We found that while carbon starvation resulted in an increased degree of infection, relative to the control, water limitation resulted in the largest degree of fungal infection. Thus, B. dothidea invaded drought-stressed xylem of potted plants more easily then irrigated plants. If the current drought persists, there will continue to be increased dieback in stands of M. laurina, which could have severe implications on the ecological stability of the Santa Monica Mountains and could increase fuel loads for fires with increased stands of dead plants.