Palmer amaranth and waterhempAn article featured in the journal Weed Science sheds important new light on the genetics and potential control of Palmer amaranth and waterhemp—two troublesome Amaranthus species weeds that are resistant to multiple herbicides.Credit: www.wssa.net

July 18, 2019 — An article featured in the journal Weed Science sheds important new light on the genetics and potential control of Palmer amaranth and waterhemp—two troublesome Amaranthus species weeds that are resistant to multiple herbicides.

While most Amaranthus species are monoecious and contain both male and female flowers on a single plant, Palmer amaranth and waterhemp are dioecious. Some plants are female, while others are male. This reproductive difference promotes outcrossing and genetic diversity, which can fuel herbicide-resistant populations.

A team based at the University of Illinois recently sequenced the DNA for both male and female Palmer amaranth and waterhemp plants to explore dioecy and the genetic basis of sex determination. The data sets they compiled from sex-specific and sex-biased sequences were able to distinguish between male and female plants from multiple, geographically distinct Palmer amaranth and waterhemp populations with a 95 percent or greater accuracy.

This new genetic-level data is expected to be of great benefit to researchers who are interested in the biology, evolution, and control of both Palmer amaranth and waterhemp.

"We hope that having a better understanding of weed genetics will open up new control strategies that haven't yet been considered," says Patrick J. Tranel, PhD, a professor at the University of Illinois. "For example, it might be possible to manipulate Palmer amaranth or waterhemp genes so that all offspring are male, causing the collapse of a local weed population."

To learn more, you can read the article "Sex-specific markers for waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri)" In Weed Science vol. 67 issue 4 online.