Presentation Title

The Effect of Water Stress on the Growth of a Fungal Pathogen, Botryosphaeria dothidea.

Start Date

November 2016

End Date

November 2016

Location

HUB 302-65

Type of Presentation

Poster

Abstract

California experienced unprecedented drought between 2012 and 2016, possibly reflecting early stages of climate change. We examined the mechanism of drought-induced mortality for a keystone chaparral species, laurel sumac (Malosma laurina) in the coastal Santa Monica Mountains. This chaparral species typically provides persistent cover in fire-prone environments due to vigorous resprout success and slope stability in rugged landscapes due to unusually deep roots penetrating soils more than 13 m. Since drought can limit the ability of native plants to block fungal infection and invasive spread, our research focused on the mechanism by which M. laurina dieback is caused by a fungal-induced decline in stem water transport. Botryosphaeria dothidea is an opportunistic fungus that has infected and killed drought stressed populations of laurel sumac shrubs throughout the Santa Monica Mountains. The fungus, which enters through a natural break in the bark of the stem, invades a Malosma laurina host and kills nutrient rich cells such as the vascular cambium, weakening plant defenses and eventually causing whole stem mortality. We investigated the ability of fungal growth at water potentials equivalent to what M. laurina experiences during California’s historic drought. This study shows that B. dothidea colonies grow effectively over a broad range between -0.43 MPa and -4.79 MPa, exceeding the biological range that M. laurina can withstand. Furthermore, fungal elongation of B. dothidea within stem segments of M. laurina held at -1.73 MPa was significantly higher than B. dothidea grown on stems with a water potential of -0.24 MPa, -3.07 MPa, -3.94 MPa, -4.42 MPa.

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Nov 12th, 1:00 PM Nov 12th, 2:00 PM

The Effect of Water Stress on the Growth of a Fungal Pathogen, Botryosphaeria dothidea.

HUB 302-65

California experienced unprecedented drought between 2012 and 2016, possibly reflecting early stages of climate change. We examined the mechanism of drought-induced mortality for a keystone chaparral species, laurel sumac (Malosma laurina) in the coastal Santa Monica Mountains. This chaparral species typically provides persistent cover in fire-prone environments due to vigorous resprout success and slope stability in rugged landscapes due to unusually deep roots penetrating soils more than 13 m. Since drought can limit the ability of native plants to block fungal infection and invasive spread, our research focused on the mechanism by which M. laurina dieback is caused by a fungal-induced decline in stem water transport. Botryosphaeria dothidea is an opportunistic fungus that has infected and killed drought stressed populations of laurel sumac shrubs throughout the Santa Monica Mountains. The fungus, which enters through a natural break in the bark of the stem, invades a Malosma laurina host and kills nutrient rich cells such as the vascular cambium, weakening plant defenses and eventually causing whole stem mortality. We investigated the ability of fungal growth at water potentials equivalent to what M. laurina experiences during California’s historic drought. This study shows that B. dothidea colonies grow effectively over a broad range between -0.43 MPa and -4.79 MPa, exceeding the biological range that M. laurina can withstand. Furthermore, fungal elongation of B. dothidea within stem segments of M. laurina held at -1.73 MPa was significantly higher than B. dothidea grown on stems with a water potential of -0.24 MPa, -3.07 MPa, -3.94 MPa, -4.42 MPa.