Research Overview

We study plant-microbe interactions at the molecular level and are focused on how the microbe manipulates the plant to promote its own growth and reproduction. In parallel, we examine plant defenses that limit the extent of growth and reproduction of an adapted pathogen on its host. Furthermore, we translate our fundamental discoveries in plant-microbe interactions to promote sustainable agriculture.

Plant-Pathogen Interactions

powdery mildew
Plant-pathogen interactions are marvelously intricate, diverse, and highly integrated, with the disease outcome of the interaction dependent upon both pathogen and plant host factors and processes.

Powdery mildew infection of plants

Powdery Mildew Enveloping a Strawberry
The powdery mildew Golovinomyces orontii is an obligate fungal biotroph that alters plant cellular architecture and metabolism to acquire all of its nutrients, including carbon and nitrogen, while limiting plant defensive responses including cell death. G. orontii is uniquely suited to spatially and temporally resolved analyses as (i) its structural development and progression of disease on A. thaliana is well-defined, limited to epidermal cells, visible by light microscopy, and quantifiable, and (ii) host responses are typically focused at the site of infection. Much work on powdery mildew-host interactions has focused on early stages of the interaction including factors required for penetration and/or formation of the haustorial complex, the fungal feeding structure. My laboratory focuses on the later phase of a compatible interaction, the extensive external growth and reproduction of the powdery mildew, shown below at 5 days post infection (5 dpi). Analysis at this later infection stage allows us to identify factors required to support the sustained extensive external growth of the fungi and the development of asexual fungal reproductive structures known as conidiophores, as well as factors that limit host resistance responses.

Salicylic acid and plant defense

G. orontil infected plants
The phytohormone salicylic acid, 2-hydroxybenzoate, has long been known to accumulate in plants in response to diverse pathogens including viruses, bacteria, and fungal biotrophs and to be required for both local and systemic resistance responses. because phytohormones control critical biological processes, the concentration and locale of active phytohormone is tightly regulated, with both syntheis and modification of the phytohormone playing important roles (Wildermuth, COPB 2006). Compared with other phytohormones, such as the growth regulator indole acetic acid (IAA), our understanding of the synthesis, chemical modification, and regulation of SA, as well as its receptor(s), specific mode(s) of action, and impacted genes and processes is quite limited. Here at UC Berkeley , my laboratory has built on my previous finding that the bulk of pathogen-induced SA is synthesized from chorismate via isochoristmate synthase 1 (ICS1) in Arabidopsis (Wildermuth et al. Nature 2001) to (i) explore the transcriptional impact of SA and the regulatory circuitry of its response and (ii) identify biochemical control points impacting SA accumulation and activity. Ultimately,, our research may facilitate crop tolerance of (a) biotic stress, our understanding of the mechanisms of action of aspirin (active agents: salicylate) in humans, and the impact and integration of stress hormones with those mediating growth and development.

Bakar Fellowship - Improve Crop Resistance to Powdery Mildews

The Bakar Fellows Program Fellowship allows Wildermuth to apply her basic research on powdery mildew infection of plants to enhance crop resistance to powdery mildews. Powdery mildews are widespread pathogens that infect grapevine, tomatoes, strawberries, lettuce, and many other important CA crops. These crops are susceptible to powdery mildews and are currently treated repeatedly with chemicals to limit initial infection and propagation through an agricultural field. Powdery mildews get all of their nutrients from the plant. By limiting the ability of the powdery mildew fungus to get the specific nutrients it requires to grow and reproduce, Wildermuth hopes to enhance powdery mildew resistance in the field, thereby limiting the use of fungicides.

Funding

Our research is currently funded by the National Science Foundation (NSF), American Vineyard Foundation (AVF), and the Gloeckner Foundation.