Natalie’s paper accepted to Plant Disease

Our lab recently had a short paper (a disease “note”) accepted to the journal Plant Disease! The paper is titled “First Report of Botryosphaeria dothidea Causing Stem Canker and Plant Death in Malosma laurina in Southern California.” Pepperdine graduate (class of 2017) Natalie Aguirre is the lead author on the paper.

Natalie examining an infected Malosma laurina

Over the last couple years, Natalie has investigated a serious fungal infection in Malosma laurina, a co-dominant chaparral shrub species on Pepperdine campus. M. laurina (laurel sumac) is an important member of the chaparral plant community throughout the Santa Monica Mountains in Malibu, CA. In the past, this shrub has been very resistant to the effects of drought because of its deep roots that access deep water resources. While shallow-rooted plants experience dehydration, M. laurina has remained relatively hydrated.

Natalie standing inside a healthy M. laurina

However, in 2015 we noticed severe dieback in M. laurina along the coastal exposures of the Santa Monica Mountains. A fungus appears to be blocking water transport in the vascular system, cutting off water supply to the leaves. We suspect that the extended drought of 2012-present may have pre-disposed the plants to be more susceptible to this infection, perhaps by weakening their immune systems or limiting their carbon resources. In the photo below, you can clearly see where the point in the stem where the fungus is growing and blocking water supply to the leaves.


Check out Natalie’s paper when it becomes available online! Also, she has presented this research at the Ecological Society of America (2017) and the Botanical Society of America (2016). You can read her abstracts here:

Natalie’s ESA abstract (2017)

Natalie’s BSA abstract (2016)

There are many student authors on this paper because this was a collaboration of many people in Dr. Davis’ lab! His Plant Physiology class (fall 2015) conducted their class projects on the M. laurina infection. Thanks to everyone’s hard work, we learned a lot about the nature of the fungal infection.

Plant Physiology class excavating M. laurina roots
Plant Physiology class poster session

Natalie is currently working on a research Fulbright in Madrid, Spain. We are excited to see the great things in store for her!


Photo credits: Dr. Steve Davis


Santa Cruz Island, January 2018

Earlier this month, several of us took a field trip to Santa Cruz Island to continue our research project on foliar water uptake in island ferns. This time, we were transplanting island ferns to the mainland for further experiments.

As always, the boat ride was fantastic! Dolphins followed us part of the way, and the fog was clearly visible around the island as we approached.

The island has many different microsites with small differences in climate. Thus, we needed to travel all over the island to locate our eight diverse fern species!

Many of the fern species were located near the west end of the island in Christy Pines. This seems like a logical place for the ferns to grow because this west end of the island is frequently foggy. After collecting the ferns, we continued past Christy Pines to Christy Beach.

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Gaby at Christy Beach

The next day, we drove back to the dock at Prisoners’ Harbor. From there we hiked to Pelican Bay, where the rest of our fern species grow. There is a small perennial water source near Pelican Bay, and many of the dehydration sensitive evergreen ferns grow there.

It was certainly a successful trip! I am excited for the experiments we will run over the next few months, and I am definitely looking forward to returning to the island.

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Leaving Santa Cruz Island