Plant Pathology Grad Student Receives Fellowship to Study Grapevine Disease

A graduate student in Penn State's College of Agricultural Sciences has received a three-year Graduate Research Fellowship from the National Science Foundation, valued at more than $100,000, to study how climate change is affecting diseases that rot grapes.

Jamie Spychalla, a doctoral degree candidate in the Department of Plant Pathology and Environmental Microbiology, will investigate how plant phenotype and the environment affect microbial-plant interactions.

"My ultimate goal is to inform future modeling of plant diseases in different environments," said Spychalla, who is advised by Sharifa Crandall, assistant professor of soilborne disease dynamics and management. "Using Vignoles grape and the sour rot disease complex as models, we'll address how spatial differences within a grape cluster and microclimate impact plant-microbe interactions."

Climate change is shifting the biology of microbes and their host plants, and understanding the mechanisms behind their response is critical for predicting plant survival and health, Spychalla explained. Seasonal fluctuations in weather, which operate on a shorter timescale than climate, can impact the timing and intensity of host-microbial interactions that are caused by pathogenic microbes.

Grape clusters are an excellent model for investigating plant-microbe-environmental interactions because there are a plethora of grape phenotypes that provide a range of host responses to measure, Spychalla said.

"Loose versus tightly arranged grape clusters typically harbor less disease," she said. "One way to loosen clusters in the field or greenhouse is by using plant hormones, but I learned from my preliminary work in the field that it is difficult to get consistent results, so we pivoted to researching clusters that are bred to be loose as well as pruning leaves as a cultural practice to affect cluster looseness."

As part of her study, researchers will treat, sample and test grapes from Penn State's Lake Erie Regional Grape Research and Extension Center and the Michigan State Clarksville Research Station. They will insert 50 iButton temperature and relative humidity loggers into grape clusters, and the microclimate data they generate will be collected at the end of summer and analyzed by Spychalla and colleagues.

Crandall noted that Spychalla's research will contribute to the knowledge of disease ecology of other plants with small fruits such as berries, both in managed and wild ecosystems.

"Understanding biotic plant stress under different host phenotypes and environmental conditions is important for building more robust disease-forecasting models as a baseline for modeling longer-term effects of climate change," Crandall said.