A team of Agricultural Research Service scientists has reported a biotechnological approach that enables crop species to produce, or to increase production of, the phytochemical compound pterostilbene. Stilbenes are a subgroup of phytochemicals called “polyphenols.” The approach could pave the way for ramping up levels of potentially healthful pterostilbene in crops that normally produce it, such as grapes and berries.
Molecular biologists Scott R. Baerson and Zhiqiang Pan, and chemist Agnes Rimando, headed the study. They and plant physiologist Franck Dayan, a coauthor, are with the Natural Products Utilization Research Unit in Oxford, Mississippi. Also a coauthor, ARS plant pathologist James Polashock is with the Genetic Improvement of Fruits and Vegetables Lab in Beltsville, Maryland, but based in Chatsworth, New Jersey.
There are two stilbenes—resveratrol and pterostilbene—which may possess similar purported beneficial health properties. During their work, the team showed that a previously characterized and patented gene (SbOMT3), which they had isolated from the sorghum plant, is capable of converting resveratrol to pterostilbene. They then built on that conversion activity by co-expressing SbOMT3 with a stilbene-synthase gene (AhSTS3) that had been isolated from the peanut plant. The approach was then tested in transgenic plants of two different species that do not naturally produce pterostilbene.
For the proof-of-concept study, both genes were successfully incorporated into the chromosomes of two different model host plants, Arabidopsis and tobacco. The two-gene strategy generated transgenic plants that were able to produce pterostilbene, the authors reported.
It is unknown whether most phytochemicals are well absorbed in the body. But based on animal-model studies conducted by other scientists, pterostilbene has significantly higher bioavailability than the parent compound resveratrol.
The study results were published in Plant Biotechnology Journal in 2012.
The USDA-ARS patent on the ability of SbOMT3 to produce transgenic plants that express pterostilbene, which also describes the two-gene strategy, was issued in 2010. The ARS Office of Technology Transfer works with companies interested in obtaining required regulatory approvals, licensing ARS technologies, and conducting trials.—By Rosalie Marion Bliss, Agricultural Research Service Information Staff.
"Ramping Up a Phytochemical Compound in Crops" was published in the November/December 2013 issue of Agricultural Research magazine.