If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



Engineered cotton grows on alternative fertilizer

Crop feeds on phosphite, potentially allowing it to outwit weeds and mitigate pollution from traditional fertilizer runoff

by Carmen Drahl
June 17, 2018 | A version of this story appeared in Volume 96, Issue 25


Photo depicts a field of cotton overrun by Palmer amaranth, also known as pigweed, a plant that has developed resistance to the herbicide glyphosate.
Credit: Texas A&M AgriLife
Pigweed infests a Texas cotton field.

Wily weeds can develop resistance to herbicides, allowing them to compete with genetically modified crops designed to tolerate weed-killing chemicals. Now, a team is proposing another approach to genetically engineering crops to outgrow weeds: cotton that feeds on an alternative fertilizer, one that weeds can’t use (Proc. Natl. Acad. Sci. USA 2018, DOI: 10.1073/pnas.1804862115).

Photo depicts a Texas cotton field with one cotton plant viewed up close.
Credit: Plains Cotton Growers
Later this month, researchers will test the new transgenic cotton in a Texas field like this one.

“This work is exactly the sort of genetic engineering that I would like to see more of, traits that expand the realm of what farmers can do while protecting the environment,” says Anastasia Bodnar, a plant geneticist who was not involved with the work and is the policy director for Biology Fortified, a nonprofit organization that fosters discussion on biotechnology and agriculture.

Regular plants need phosphate to grow, but the new cotton can survive on phosphite instead because the crop is engineered to contain a bacterial gene that confers the ability to convert phosphite to phosphate, explains Luis Herrera-Estrella of Mexico’s National Laboratory of Genomics for Biodiversity, who co-led the work with Texas A&M University’s.

Keerti Rathore. Their combined teams developed transgenic cotton that grows just as well on phosphite as regular cotton grows on phosphate. In soils with varied chemical and nutrient profiles, the plants outcompeted a bane of cotton farmers’ existence: Palmer amaranth, or pigweed, which resists the common herbicide glyphosate. The first trials outside the greenhouse commence later this month in Texas. A spin-off company cofounded by Herrera-Estrella, StelaGenomics, is developing the technology for use with other crops.

Phosphite is used to kill fungi in crops, but manufacturers would need to scale up production to accommodate fertilizer demands, if this strategy ever reaches widespread use. Farmers might be able to apply less phosphite than they would phosphate, Bodnar says. Phosphate can run off farmlands into waterways, where the compound promotes the growth of toxic and harmful algal blooms. But phosphite should be used carefully, Bodnar adds, because long-term use might select for bacteria in soil and waterways that convert phosphite to phosphate, thus recreating the phosphate problem.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.