SEPTEMBER 2017 SEEDWORLD.COM / 57 Adding to the success of that initial seed testing development, the University of Illinois’ Pat Tranel, a molecular weed scientist, and graduate student Brent Murphy developed a way to identify Palmer amaranth DNA from within a mixed seed sample without having to grow the plants or test individual amaranth seeds. The assay, which uses a method known as quantitative PCR, can detect genetic variations unique to Palmer amaranth even when flooded with samples from closely related species, including waterhemp. “Palmer, redroot pigweed, waterhemp – they all have tiny black seeds that basically look the same,” Tranel says. “We needed a way to efficiently extract DNA from pooled seed samples and, if it’s present, identify Palmer.” This type of testing brings the ability to test for Palmer amaranth to every stage of the seed cleaning process. Doug Miller, CEO of the Illinois Crop Improvement Association, applauds the development of the test. He says it’s not uncommon to find hundreds of amaranth seeds in an unclean or raw seed sample taken just after harvest. Testing of hundreds of individual seeds is expensive, which makes cleaning the lot prior to testing more attrac- tive. After the lot is cleaned, pack- aged and ready for sale, a sample is submitted and any remaining amaranth seeds can be tested. Now with the new bulk method, he says testing prior to cleaning makes more sense. “I would want to test all of the pigweed seeds found in the raw seed sample,” says Miller. “In my opinion, the raw sample would better represent what species were present in the seed producer’s field.” Diane Plewa and Elizabeth Phillippi at the University of Illinois Extension Plant Clinic optimized the test for routine commercial use and up to 100 pigweed seeds can be tested for $50. The Illinois Crop Improvement Association created a blind sample set for final validation of the method. The Plant Clinic results were a 100 percent match, identify- ing Palmer amaranth from three different sources at different levels within each pigweed sample. With that kind of detection abil- ity, the assay can also be used to estimate the percentage of pig- weeds that are Palmer amaranth by using a statistical calculator such as SeedCalc. Two pools of 100 pigweed seeds each, one neg- ative and one positive for Palmer amaranth, would indicate that Palmer amaranth is approximately 1.5 percent among the pigweed seed in the lot using a confidence level of 95 percent. Innovations such as these two tests to detect Palmer amaranth help to advance the seed industry and ensure farmers receive the best seeds possible to plant in their fields. SW A single Palmer amaranth plant can produce as many as a million seeds during the growing season. DID YOU KNOW? Phone: (800) 418-9461 Email: conveyors@convey-all.com convey-all.com At every step, Convey–All’s seed tenders, conveyors, and bulk systems deliver. DEPENDABLE. FUNCTIONAL. RELIABLE. Phone: (800) 418-9461 Email: conveyors@convey-all.com At every step, Convey–All’s seed tenders, DEPENDABLE. FUNCTIONAL.