Satchivi Norbert M, deBoer Gerrit J, Bell Jared L
Dow AgroSciences LLC , 9330 Zionsville Road, Indianapolis, Indiana 46268, United States.
J Agric Food Chem. 2017 Aug 30;65(34):7328-7336. doi: 10.1021/acs.jafc.7b01453. Epub 2017 Aug 17.
Green foxtail [Setaria viridis (L) Beauv.] and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult.] are among the most abundant and troublesome annual grass weeds in cereal crops in the Northern Plains of the United States and the Prairie Provinces of Canada. Greenhouse and laboratory experiments were conducted to examine the differential responses of both weed species to foliar applications of the new triazolopyrimidine sulfonamide acetolactate synthase-inhibiting herbicide, pyroxsulam, and to determine the mechanism(s) of differential weed control. Foliar applications of pyroxsulam resulted in >90% control of yellow foxtail at rates between 7.5 and 15 g ai ha, whereas the same rates resulted in a reduced efficacy on green foxtail (≤81%). The absorption and translocation of [C]pyroxsulam in green and yellow foxtail were similar and could not explain the differential whole-plant efficacy. Studies with [C]pyroxsulam revealed a higher percentage of absorbed pyroxsulam was metabolized into an inactive metabolite in the treated leaf of green foxtail than in the treated leaf of yellow foxtail. Metabolism studies demonstrated that, 48 h after application, 50 and 35% of pyroxsulam in the treated leaf was converted to 5-hydroxy-pyroxsulam in green and yellow foxtail, respectively. The acetolactate synthase (ALS) inhibition assay showed that ALS extracted from green foxtail was more tolerant to pyroxsulam than the enzyme extracted from yellow foxtail was. The in vitro ALS assay showed IC values of 8.39 and 0.26 μM pyroxsulam for green and yellow foxtail, respectively. The ALS genes from both green and yellow foxtail were sequenced and revealed amino acid differences; however, the changes are not associated with known resistance-inducing mutations. The differential control of green and yellow foxtail following foliar applications of pyroxsulam was attributed to differences in both metabolism and ALS sensitivity.
绿狗尾草[Setaria viridis (L) Beauv.]和黄狗尾草[Setaria pumila (Poir.) Roem. & Schult.]是美国北部平原和加拿大草原省份谷类作物中分布最广、最麻烦的一年生禾本科杂草。进行了温室和实验室试验，以研究这两种杂草对新型三唑并嘧啶磺酰胺类乙酰乳酸合成酶抑制除草剂双氟磺草胺叶面喷施的不同反应，并确定不同杂草防除机制。叶面喷施双氟磺草胺，用量在7.5至15克有效成分/公顷之间时，对黄狗尾草的防除效果>90%，而相同用量对绿狗尾草的防除效果降低（≤81%）。[C]双氟磺草胺在绿狗尾草和黄狗尾草中的吸收和转运相似，无法解释整株植物防除效果的差异。对[C]双氟磺草胺的研究表明，与黄狗尾草处理叶片相比，绿狗尾草处理叶片中吸收的双氟磺草胺代谢为无活性代谢物的比例更高。代谢研究表明，施药48小时后，绿狗尾草和黄狗尾草处理叶片中分别有50%和35%的双氟磺草胺转化为5-羟基双氟磺草胺。乙酰乳酸合成酶（ALS）抑制试验表明，从绿狗尾草中提取的ALS比从黄狗尾草中提取的酶对双氟磺草胺更具耐受性。体外ALS试验表明，绿狗尾草和黄狗尾草的双氟磺草胺IC值分别为8.39和0.26 μM。对绿狗尾草和黄狗尾草的ALS基因进行了测序，发现了氨基酸差异；然而，这些变化与已知的抗性诱导突变无关。叶面喷施双氟磺草胺后对绿狗尾草和黄狗尾草的防除差异归因于代谢和ALS敏感性的差异。
