Sequencing ALS in Annual Bluegrass: Implications for Herbicide Resistance.
|Author:||NM Kaufman, SD Askew, JB Beam, and WL Barker|
|Author Org:||Virginia Tech|
|Conference:||Northeastern Weed Science Society|
|Abstract:||The number of herbicides registered for use in turfgrass that inhibit acetolactate synthase (ALS) has increased from four to nine in the last two years. The four ALS-inhibiting herbicides registered for use in turfgrass prior to 2001 include chlorsulfuron, halosulfuorn, metsulfuron, and imazaquin. These four herbicides were originally marketed for purposes other than annual bluegrass control, but some of them are often used for that purpose. However, of the five ALS-inhibiting herbicides registered since 2001, bispyribac-sodium, foramsulfuron, rimsulfuron, and trifloxysulfuron are marketed predominately for annual bluegrass control and sulfosulfuron can be used for that purpose. These herbicides constitute a major change in use patterns for annual bluegrass control in turfgrass and increase the chances of selecting for ALS-resistant biotypes of annual bluegrass. Assuming that molecular based resistance to ALS-inhibiting herbicides will occur in annual bluegrass as it has in other weeds, it is desirable to gather information that would help predict the nature of potential resistance and how one would avoid it. Our attempt at sequencing the ALS gene in annual bluegrass was an effort to identify any highly variable regions that may relate to gene mutations eliciting resistance to newly-registered turfgrass herbicides. Custom primers were designed using the highly conserved regions of the ALS gene of the closely related plant species barley (Hordeum vulgare), rice (Oryza sativa), Italian ryegrass (Lolium multiflorum), and corn (Zea mays). Genomic DNA was extracted from annual bluegrass using the Qiagen DNeasy Plant Mini Kit. The ALS region of annual bluegrass genome was then PCR amplified using custom designed primers. The amplicon was cloned into an Invitrogen TA cloning vector and sequenced using Applied Biosystems BigDye 3.1 sequencing chemistry. Future work will include analysis of the sequence data, identifying variable regions, performing ALS point mutations, and enzyme studies.|