Wednesday Nite at the Lab
press release: For the fall semester, WN@TL goes hybrid both with Zoom and with in-person (Room 1111) presentations. The zoom registration link is still go.wisc.edu/240r59. You can also watch a live web stream at on YouTube.
On July 27 Dennis Halterman of the USDA Ag Research Service’s Vegetable Crops Unit here at UW-Madison will get to the root of all goodness with his talk on “Building a Better Potato: Fighting Diseases at the Molecular Level.”
Description: In the U.S., potato annually accounts for $3.94 billion in market value and the crop is grown on just under one million acres. Wisconsin is the third-largest producer of potatoes in the US. The vast majority of varieties are extremely susceptible to several diseases, requiring intensive management that incorporates cultural practices and preventative fungicides to prevent crop losses. The development of disease resistant germplasm will reduce the need for chemical applications and will also provide a stable food source with a reduced risk of disease epidemics.
In nature, microbes interact with plants on an enormous scale. Phytopathogens utilize hundreds of molecules, termed ‘effectors’, to manipulate and infect their hosts. The cumulative effect of these proteins on the plant allows the pathogen to avoid defenses and obtain the nutrients it requires to proliferate. In order to combat this molecular onslaught from phytopathogens, plants have evolved genes that encode receptors for key effectors. These ‘resistance gene’ products function to recognize the presence of specific effector molecules presented by the invading pathogen. This recognition event results in a rapid signal cascade, leading to a much stronger and longer lasting active defense response. This response typically culminates in programmed cell death of the host cell and surrounding cells, which is thought to restrict pathogen spread by limiting the availability of nutrients to the pathogen.
Wild potato species are found in highly diverse habitats, including cloud forests, cactus deserts, scrub vegetation, mountain pastures, high grasslands, and pine forests throughout Central and South America. They carry genes for traits that have not been identified in cultivated potato and are a rich source of stress resistance and tuber quality genes. Reports of disease and pest resistance in wild and cultivated relatives of potato are abundant and potato breeders have used wild relatives as sources of disease resistance and improved quality for over 150 years. However, despite our best efforts to control diseases through the introduction of resistance into new varieties, pathogen populations continue to change to overcome resistance. This occurs through adaptation of effector ‘toolboxes’ within the pathogen to avoid detection by the plant or to actively suppress plant defenses. Our work is focused on understanding the mechanisms of how pathogens ‘break’ resistance in potato, and developing strategies that will help us keep up with rapid changes within pathogen populations.
Bio: Dr. Halterman grew up as the child of science and algebra teachers. During the summers, he worked on his extended family’s farms in north-central Illinois, helping to raise 1500+ acres of corn and soybeans. This combination of science, math, and agriculture influenced his decision to major in biology and biochemistry at Cornell College in Mt. Vernon, Iowa and he went on to complete a Ph.D. at Purdue University studying tomato disease resistance.
Dr. Halterman studied powdery mildew resistance in barley as a USDA/ARS postdoc before accepting his current position in 2004 with the USDA in Madison, Wisconsin. Since then, his research group has worked to identify new sources of disease resistance in wild relatives of potato and understand their role in recognizing pathogens and activating resistance. His work has led to the identification of new sources of resistance to potato late blight and a better understanding of the molecular mechanisms of resistance to late blight, PVY, verticillium, and other diseases.
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