While most amaranthus species have 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 the development and spread of herbicide resistant populations.

A team of researchers 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.

What does this mean for the future of weed control?  Scientists hope that having a better understanding of weed genetics will lead to new breakthroughs in weed management. It is easy to imagine how genes might be modified to ensure that all offspring from Palmer amaranth and waterhemp plants in a given location would be of the same sex – causing the population to collapse.

Want to learn more? You can read the article “Sex-specific markers for waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri)” in  vol. 67 issue 4 of Weed Science.

Read the WSSA press release here.