Why this newfound trait in corn could be a force against crop disease

NC State researchers discovered a gene that shows unique resistance against multiple crop diseases. 

Why this newfound trait in corn could be a force against crop disease

September 19, 2017

Just like people, plants get sick. Discolored spots grow on the leaves and black bruises appear on roots and fruit until the plant cannot even grow properly.

Grey Leaf SpotIn the garden, the totality of these diseases’ effects could be some unattractive leaves or wilting flowers. But when these diseases hit crops, a fast-spreading disease could wipe out entire crops and threaten the food supply.

That is why crop scientists, through guided pollination or genetic modification, are constantly trying to create crops that are immune to powerful infections. Now researchers from North Carolina State University have found a single gene in some strains of corn that confers resistance to multiple devastating infections. The research was published in the journal Nature Genetics.

The gene allows corn to hold off Southern Corn Leaf Blight, Grey Leaf Spot and possibly Northern Corn Leaf Blight, three fungal diseases that have caused billions of dollars in damage to U.S. corn crops over the past several decades.

Qin Yang, a postdoctoral researcher at NC State and one of the authors of the study, used a technique called genetic fine mapping to narrow down the possible genes that could be causing the resistance. Fine mapping references large databases of genetic variations to isolate the cause of a specific trait, and Yang’s work isolated a selection of four genes out of hundreds that could be responsible for the immune corn.

Grey Leaf SpotIt is a slow, painstaking process that USDA plant pathologist and co-author of the study Peter Balint-Kurti likened in a press release to finding a single, specific restaurant in a large city without directions or GPS.

Four genes were narrowed to one with the help of collaborators from the USDA and universities around the country. The gene itself is called CCOAOMT1 and it has a few specific functions. It is involved in creating an enzyme called caffeoyl-CoA O-methyltransferase, which in turn helps in the building and reshaping of complex sugar molecules. It also works in the production of lignin, a polymer that gives plants their structure and gives wood its “woodiness” when compared to other plants. All three of the previously mentioned corn diseases involve dead, withered cells that turn grey or brown and crumble. Yang says more robust lignin production tends to prevent 1 from taking hold in corn leaves, and in the case of this particular gene, that appears to hold true.

It is important to note that this single gene only gives partial immunity to these fungal infections. Balint-Kurti says total resistance comes from a combination of many genes. What makes this discovery so special is the fact that it promotes resistance to multiple species of infectious fungi. Both selective breeding and genetic modification to express a specific gene are tricky, so any gene that can provide resistance to two or three diseases for the price of one is a major find, especially when the crop in question produces 15 billion bushels from 90 million acres annually in the U.S.

Crop diseases will continue to be a concern as the population and demand for food continue to grow, but studies like this can help to guarantee a robust food supply and potential fuel source for generations to come.

Daniel Lane

Daniel Lane covers science, medicine, engineering and the environment in North Carolina.

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