Botany and Plant Pathology Seminar Series
Speaker: Dr. Martin Dickman - Christine Richardson Professor and Director,Institute for Plant Genomics and Biotechnology - Texas A & M University
Topic: Modulation of Programmed Cell Death for Fungal Disease Development/Stress Tolerance in Plants
When: Wednesday, February 06, 2013 at 3:30 pm in WSLR 116

We study Sclerotinia sclerotiorum, an economically important, broad host range necrotrophic fungal phytopathogen. For successful infection, this fungus hijacks host pathways and induces plant apoptosis. A principal component for pathogenic success is oxalic acid (OA), a fungal secreted virulence determinant. This “simple”organic acid is remarkably multi-functional, not only as an elicitor of apoptosis, but also in cell redox alteration creating a reductive stress environment in the host, prior to a transition to oxidative stress induced plant PCD. OA mutants are non-pathogenic and when inoculated to plant hosts, instead of apoptosis, autophagy occurs.

Although plant cells undergo apoptotic-like cell death, plant homologs of mammalian regulators of apoptosis have in general, been elusive. This is in part due to the lack of primary sequence conservation between animal and potential plant regulators of apoptosis. Thus alternative approaches to identify plant cell death regulators are needed. Using bioinformatic tools we uncovered the Arabidopsis family of BAG proteins. The mammalian BAG (Bcl-2-associated athanogene) proteins are a family of co-chaperones that modulate diverse processes ranging from proliferation to growth arrest and cell death. Our studies have shown that plant BAG members are also multi-functional and remarkably similar to their animal counterparts, as they regulate apoptotic-like processes ranging from pathogen defense, to abiotic stress, to development. In particular, the vacuole localized plant AtBAG6 will be described. Knockout of AtBAG6 results in the loss of non-host resistance to fungi via blocking of autophagy.

Our recent identification of a potential Sclerotinia effector protein that is associated with biotrophy maintanence will be discussed and lastly, we will discuss our efforts generating  disease/stress tolerant transgenic crop plants using genes that regulate cell death.


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