Presentation Title

Drought-Induced Fungal Infection Causes Severe Dieback in Malosma laurina in the Santa Monica Mountains

Presentation Type

Oral Presentation

Keywords

Drought, canker, Malosma laurina, fungus, photosynthesis, Botryosphaeria dothidea

Department

Biology

Major

Biology

Abstract

The current unprecedented drought in California has reached maximums may predisposes plants to fungal infection. Dieback shrubs have shown external wounds, known as cankers, which signals the plant’s immune response to infection. The invading fungus enters through this wound; once inside, it travels through the xylem, thus blocking water transport from the soil to the leaves and thus decreasing photosynthetic rate. Our hypothesis was that photosynthetic rates in Malosma laurina will be high in healthy control resprouts, intermediate in young dieback resprouts, and low in old dieback resprouts with cankers. M. laurina, a chaparral shrub, was used because it is drought-tolerant, has deep roots, has a 99% success rate of resprouting after fires, is co-dominant with other chaparral shrub species, and is a keystone species. To test this hypothesis, a chaparral shrub, M. laurina, was monitored for photosynthesis, transpiration, water potential, conductance, electron transport rate, and ΦPSII using the LI-6400XT Portable Photosynthesis System. Study sites include next to the Theme Tower and at Drescher campus. We found that the control for both adults and resprouts had significantly higher photosynthetic rates than dieback plants. We also discovered that the fungus infecting the local shrubs is Botryosphaeria dothidea. From this, we can conclude that the fungus B. dothidea is causing dieback and thus lowering photosynthesis for infected shrubs. B. dothidea is able to infect the shrubs and cause devastation because the limited water access as a result of the drought causes the plants to be more susceptible to fungal infection.

Faculty Mentor

Dr. Stephen Davis

Funding Source or Research Program

Summer Undergraduate Research in Biology

Presentation Session

Session C

Location

Plaza Classroom 190

Start Date

1-4-2016 5:00 PM

End Date

1-4-2016 5:15 PM

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Apr 1st, 5:00 PM Apr 1st, 5:15 PM

Drought-Induced Fungal Infection Causes Severe Dieback in Malosma laurina in the Santa Monica Mountains

Plaza Classroom 190

The current unprecedented drought in California has reached maximums may predisposes plants to fungal infection. Dieback shrubs have shown external wounds, known as cankers, which signals the plant’s immune response to infection. The invading fungus enters through this wound; once inside, it travels through the xylem, thus blocking water transport from the soil to the leaves and thus decreasing photosynthetic rate. Our hypothesis was that photosynthetic rates in Malosma laurina will be high in healthy control resprouts, intermediate in young dieback resprouts, and low in old dieback resprouts with cankers. M. laurina, a chaparral shrub, was used because it is drought-tolerant, has deep roots, has a 99% success rate of resprouting after fires, is co-dominant with other chaparral shrub species, and is a keystone species. To test this hypothesis, a chaparral shrub, M. laurina, was monitored for photosynthesis, transpiration, water potential, conductance, electron transport rate, and ΦPSII using the LI-6400XT Portable Photosynthesis System. Study sites include next to the Theme Tower and at Drescher campus. We found that the control for both adults and resprouts had significantly higher photosynthetic rates than dieback plants. We also discovered that the fungus infecting the local shrubs is Botryosphaeria dothidea. From this, we can conclude that the fungus B. dothidea is causing dieback and thus lowering photosynthesis for infected shrubs. B. dothidea is able to infect the shrubs and cause devastation because the limited water access as a result of the drought causes the plants to be more susceptible to fungal infection.