Journal
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
Volume 61, Issue 2, Pages 278-289Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jf304675j
Keywords
absorption; herbicide resistance mechanism; noxious weed; radioactivity; translocation
Funding
- Arkansas Rice Research and Promotion Board
Ask authors/readers for more resources
Barnyardgrass biotypes from Arkansas (AR1 and AR2) and Mississippi (MS1) have evolved cross-resistance to imazamox, imazethapyr, and penoxsulam. Additionally, AR1 and MS1 have evolved cross-resistance to bispyribac-sodium. Studies were conducted to determine if resistance to acetolactate synthase (ALS)-inhibiting herbicides in these biotypes is target-site or non-target-site based. Sequencing and analysis of a 1701 base pair ALS coding sequence revealed Ala(122) to Val and Ala(122) to Thr substitutions in AR1 and AR2, respectively. The imazamox concentrations required for 5096 inhibition of ALS enzyme activity in vitro of AR1 and AR2 were 2.0 and 5.8 times, respectively, greater than the susceptible biotype. Absorption of C-14-bispyribac-sodium, -imazamox, and -penoxsulam was similar in all biotypes. C-14-Penoxsulam translocation out of the treated leaf (<= 2%) was similar among all biotypes. C-14-Bispyribac-treated AR1 and MS1 translocated 31- 43% less radioactivity to aboveground tissue below the treated leaf compared to the susceptible biotype. C-14-Imazamox-treated AR1 plants translocated 39% less radioactivity above the treated leaf and aboveground tissue below the treated leaf, and MS! translocated 54 and 18% less radioactivity to aboveground tissue above and below the treated leaf, respectively, compared to the susceptible biotype. Phosphorimaging results further corroborated the above results. This study shows that altered target site is a mechanism of resistance to imazamox in AR2 and probably in AR1. Additionally, reduced translocation, which may be a result of metabolism, could contribute to imazamox and bispyribac-sodium resistance in AR1 and MS1.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available