Scientists Crack Genetic Code for Leaf Shape in Cotton
December 20, 2016 Any child who has assembled a leaf collection can prove that plants come with an astounding array of leaf shapes, and researchers know that this variation can mean big differences in a farmer’s bottom line.
Now, a new discovery gives plant breeders key genetic information they need to develop crop varieties that make the most of these leaf-shape differences.
In a paper published December 20 in the Proceedings of the National Academy of Sciences, North Carolina State researchers and colleagues from the Danforth Plant Science Center, the U.S. Department of Agriculture and Cotton Incorporated describe how they used genomic and molecular tools to find the location of the DNA sequence that determines major leaf shape in upland cotton.
The researchers also describe how they manipulated the genetic code to alter the shape of a cotton plant’s leaves in potentially beneficial ways.
That’s a significant step forward toward developing varieties that produce higher yields at less cost to the farmer, said Dr. Vasu Kuraparthy, an associate professor with NCSU’s Department of Crop and Soil Sciences and the principal investigator for the project.
Scientists have recognized that cotton plants with leaves that have five deep lobes, like the leaves of the okra plant, offer advantages to farmers over stably yielding “normal” leaves. Dr. Ryan Andres, a postdoctoral researcher who worked as a graduate student in Kuraparthy’s lab, explained that the so-called “okra” leaves are less susceptible to boll rot than what researchers refer to as “normal” leaves. The okra leaves also allow sprays to be dispersed more evenly across the plant and are associated with higher rates of flowering and earlier rates of maturity, Andres added.
To determine if they’d found the DNA sequence that controlled major leaf shapes in cotton, researchers infected okra-leaf plants with a modified virus that silenced the target gene. That led to a temporary production of normal leaves until the plants overcame the experimental virus and reverted to okra leaf shape. The team hopes that this leaf architecture results in an ideal cotton cultivar, or ideotype, capable of combining the advantages of the two leaf shapes.
Kuraparthy and Andres said the discovery sheds light on plant variation and evolution and expands the genetic toolbox for breeders to produce superior crop varieties.
“We were able to create our ideotype, but only in a transient fashion,” Kuraparthy said. “One day we want to able to do it in a heritable manner, and the first step in that is finding the gene and proving that this is the gene and these are the polymorphisms in the gene that cause these changes. This research does that.”
“Beyond creating a leaf shape more conducive to cotton cultivation, the okra leaf type also increases the expression of photosynthetic genes, providing a link between leaf shape and the ability of plants to convert light into energy for growth,” said manuscript contributor Dan Chitwood, Ph.D., Assistant Member at the Donald Danforth Plant Science Center in St. Louis, MO.
Cotton Incorporated, a research and marketing company representing cotton, funded the research. Dr. Don C. Jones, Director, Cotton Incorporated, called the discovery a “home run” in the field of cotton breeding.
“The Cotton Incorporated Fellowship which supported Ryan was a sound investment for growers, and Kuraparthy’s leadership during this course of study was a super effort,” Jones said.
Sources – North Carolina State University, Cotton Incorporated
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