ACCase Mutations Confer ACCase Resistance in Two Phalaris minor Populations from Iran. Javid Gherekhloo1, Mohammad Rashed Mohassel1, Mehdi Nassiri Mahallati 1, Eskandar Zand2, Ali Ghanbari1, Maria Osuna Ruiz3, Juan Ruiz-Santalla4, Jean Wagner5, Rafael De Prado4; 1Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi, Iran; 2Plant Protection Research Institute, Tehran, Iran; 3Finca La Orden, Badajoz, Spain; 4Universidad de Cordoba, Cordoba, Spain; 5University of Hoenheim, Hoenheim, Germany Aryloxyphenoxy propionate herbicides (belonging to ACCase inhibitors group) are commonly used in post emergence to control grass weeds such as Avena spp and Phalaris spp in wheat and barely fields of Iran. Aryloxyphenoxy propionate-resistant Phalaris minor populations have appeared in recent years and now are present in some wheat fields in two provinces of Iran where these graminicides had been applied for several years. The biochemical and molecular basis of resistance to ACCase inhibiting herbicides of fenoxaprop and diclofop was investigated in two resistant (AR and MR4) and one susceptible (S) populations of Phalaris minor from Iran. In vitro enzyme assays revealed a herbicide resistant ACCase enzyme in both R populations. Extracted ACCase enzyme from the shoots of AR and MR4 populations was highly resistant to fenoxaprop (7- and 14-fold, respectively) and to diclofop (6- and 16-fold, respectively). The ACCase gene fragment covering potential mutation sites in these populations was amplified, sequenced, and compared. Two ACCase mutations (tryptophan-2027-cysteine, and aspartate-2078-Gly) were identified in AR and MR4 populations, respectively. 113. Molecular Study of Resistance to Aryloxyphenoxypropionate Herbicides in Winter Wild Oat (Avena ludoviciana Durieu.) Populations from Iran. Javid Gherekhloo1, Mehdi Rastgoo2, Mohammad Rashed Mohassel1, Mehdi Nassiri Mahallati1, Eskandar Zand3, Rafael De Prado4; 1Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi, Iran; 2Zanjan University, Zanjan, Iran; 3Plant Protection Research Institute, Tehran, Iran; 4Universidad de Cordoba, Cordoba, Spain To molecular study of resistance to Aryloxyphenoxypropionate herbicides in winter wild oat (Avena ludoviciana Durieu.) populations, an experiment was conducted in base of dCAPS method at Biotechnology Laboratory of Ferdowsi University of Mashhad in 2006. Thirty-eight suspected populations, sampled from Ahvaz (VR), Andimeshk (NR), Shush (SOR), Shushtar (STR), Ramhormoz (ZR), Susangerd (Dashte Azadegan) (AR), and Dezful (DR) cities of Khuzestan province-Iran, were sprayed with recommended dose of clodinafop propargyl, diclofop methyl, and fenoxaprop-P ethyl herbicides, separately. Survived populations were exposed to a dose-response assay in greenhouse with the mentioned herbicides. Then the populations with high resistance factor subjected to the molecular study. dCAPS method was carried out in three steps including PCR, enzyme digestion, and gel electrophoresis. Results showed that mutation at position 1781 of ACCase enzyme resulted in a high level of resistance in 10 wild oat populations to aryloxypropionate herbicides. Substitution of isoleucine by leucine at position 1781 of acetyl CoA carboxylase is a key point mutation conferring resistance to most ACCase inhibiting herbicides in grass weeds. Other mechanisms maybe are responsible for resistance in the rest of resistant populations in this study.

Keywords