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DILIP SHAH, PH.D.
Domain Member

Plants are amazingly adaptive at meeting environmental stresses and attacks from insects and viruses. Over the millennia and throughout millions of generations, plants have developed innovative ways to survive and prosper under harsh conditions. For example, plants have developed a first line of defense to ward off attacking fungi. Called defensins, these natural defense proteins are an area of focus for the laboratory of Danforth Center scientist Dr. Dilip Shah.

The study of plant defensins is a relatively new area of research in plant science but is vital to modern agriculture, as an effective and sustainable control of fungi remains elusive. In the U.S., a variety of fungi result in hundreds of millions of dollars in losses for potato, wheat, and barley farmers each year. In developing countries, fungi are particularly devastating to subsistence farmers. Serious diseases caused by fungi are usually controlled by chemical fungicides that the farmer applies to crops.

“This discovery will allow us to better understand how plant defensins inhibit fungal growth.”

Three-dimensional structures of the plant antifungal defensin Rs-AFP1, the scorpion toxin and the fungal toxin KP4 are shown. All three proteins share a common structural element called cysteine-stabilized alpha/beta motif. The three-dimensional structure of Rs-AFP1 is shared by all plant defensins known to inhibit the growth of fungi.

Recently, Dr. Shah’s lab found at least eighteen different defensin genes in a model legume. Dr. Shah and his colleagues are examining ways to transfer the insight gained from this research to confer enhanced resistance to fungi in crop plants.

Dr. Shah has been studying defensins throughout his career, looking for ways to improve potatoes against fungal attack. Some years ago, while working at Monsanto, his research team developed a genetically modified variety of potato with enhanced resistance to fungal disease.

"Building on my previous research, my lab at the Danforth Center has further explored defensins and discovered for the first time, in collaboration with Dr. Tom Smith of the Danforth Center and Dr. Greg Hockerman of Purdue University, that a plant defensin blocks a calcium channel," explained Dr. Shah. "This discovery will allow us to better understand how plant defensins inhibit fungal growth and will facilitate genetic modification of crops for enhanced resistance to fungal attacks using defensins."

Dr. Shah’s discovery will be important to controlling the growth of fungi, as calcium channels are used as a communication network by the fungus to direct its spread. By disrupting the calcium pathway, Dr. Shah aims to inhibit fungi growth.

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