Assessing Genetic Variation and Spread of Phalaris minor Resistant to ACCase Inhibiting Herbicides in Iran

ABSTRACT: Littleseed canarygrass (Phalaris minor) is the second most serious and problematic grass weed in wheat fields in Iran, and has developed resistance to ACCase inhibiting herbicides. Inter-simple sequence repeat (ISSR) analysis was used to assess genetic variation between and within ACCase inhibitor-resistant and susceptible P. minor populations in Iran and to determine the origin of resistance and its dispersal. Sixteen P. minor populations from different regions in Iran were analysed using seven primers. Genetic relationships generated using UPGMA analysis indicated the presence of more than one genotype among the herbicide resistant populations. The results indicated that the high genetic similarity and physical proximity among the resistant P. minor populations in the different regions is mainly due to cross pollination, mechanical seed dispersion and local ecological factors. These findings suggested that independent selection as well as movement of resistant seeds had occurred, which could explain the presence and dispersion of ACCase inhibitor-resistance in these populations.