Research Summaries
Investigating the Mode of Action of Methiozolin: Cell Wall Biosynthesis Inhibition Versus Tyrosine Aminotransferase Inhibition
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ethiozolin is a new herbicide developed by Moghu Research Center for the safe and selective removal of annual bluegrass (Poa annua) from creeping bentgrass putting greens. Although this herbicide has proven very effective at controlling annual bluegrass, there is some dispute as to the mode of action of this chemical. Previous research has presented evidence that methiozolin inhibits cell wall biosynthesis and that it may be an inhibitor of tyrosine
Demonstration of how 4-HPP feeding improves duckweed growth in presence of methiozolin but has no affect on Poa annua (annual bluegrass) response to methiozolin.
aminotransferase (TAT). TAT is an important enzyme in the pathway that creates tocopherols (Vitamin E compounds) and plastoquinones (molecules involved in photosynthesis). Since all previous research on methiozolin mode of action was conducted on model species, our goal was to test for proposed mode of action affects on annual bluegrass, the primary targeted weed of methiozolin. As reported in the literature, methiozolin inhibits the incorporation of 14C-labeled glucose into the cellulose and hemicelluloses fractions of the cell wall. To further investigate this effect, we utilized 13Cglucose, a different, stable isotope of carbon, to trace the incorporation of labeled glucose into the sugar constituents of the cell wall of annual bluegrass, creeping bentgrass, perennial ryegrass and tall fescue. Methiozolin inhibited 13 C- glucose incorporation into rhamnose, arabinose and galactose approximately 30%, regardless of species and equivalent to the known CBI, indaziflam. In addition, overcoming potential TAT inhibition
Roughstalk Bluegrass Control in Creeping Bentgrass and Kentucky Bluegrass Fairways Virginia Tech Researchers: Sandeep S. Rana, Doctorate Student, and Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist Researcher Cooperator: Suk J. Koo, Ph.D., Moghu Research Center, Daejeon, South Korea Research Sponsor: Moghu Research Center, Daejeon, South Korea
28 | Virginia Turfgrass Journal May/June 2015 www.vaturf.org
Virginia Tech Researcher: Kate Venner, Graduate Research Assistant, Shawn D. Askew, Ph.D., Associate Professor and Extension Turfgrass Weed Specialist, and Eva Colla’kova’, Assistant Professor Research Cooperator: Suk J. Koo, Ph.D., Moghu Research Center, Daejeon, South Korea Research Sponsor: Moghu Research Center, Daejeon, South Korea with 4-hydroxyphenylpyruvate (4-HPP) feeding had no influence on cell wall inhibition. Further research is warranted to determine if cellulose or hemicellulose sugars are affected differently, or if reduced incorporation is simply indicative of reduced growth via a different pathway. Several studies have been initiated investigating TAT inhibition as a potential mode of action of methiozolin. Previous research using a species of duckweed implicated TAT inhibition by feeding plants with exogenous 4-HPP, a downstream product of this pathway. As a result of this feeding, duckweed recovered from methiozolin treatment. In studies at Virginia Tech, we have been able to reduce methiozolin impacts on duckweed through 4-HPP feeding, but such feeding has had no influence on annual bluegrass or other turfgrass species response to methiozolin. Although these studies are not yet concluded, current data suggest that methiozolin may not affect TAT in turfgrasses like it does in duckweed, or 4-HPP can’t efficiently alleviate such effects. c
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oughstalk bluegrass (Poa trivialis) is one of the most troublesome weeds of creeping bentgrass and Kentucky bluegrass fairways. Chemical control options for roughstalk bluegrass are limited in cool-season turf. Under development by Moghu Research Center, methiozolin (Poa Cure) is a new isoxazoline herbicide that has been reported in Virginia and Korea to control roughstalk bluegrass with safety to creeping bentgrass, perennial ryegrass, Kentucky bluegrass and tall fescue. Our objectives were to compare various application timings and