Non‐Mendelian inheritance of gene amplification‐based resistance to glyphosate in Hordeum glaucum (barley grass) from South Australia

BACKGROUND Hordeum glaucum Steud. is an important grass weed species in South Australia that has evolved resistance to glyphosate. This study investigated the mode of inheritance of glyphosate resistance in this species. RESULTS Hand‐pollination of glyphosate susceptible and resistant populations generated two F1 individuals, selfed to yield F2 progenies. In dose–response experiments, the F2 progenies showed intermediate response between the two parent populations. High variation in EPSPS gene copies was observed among F2 individuals, with some individuals possessing more gene copies than the resistant parent population. No evidence of a Mendelian single‐gene pattern of inheritance was observed. CONCLUSION Inheritance of gene amplification in H. glaucum is non‐Mendelian. © 2021 Society of Chemical Industry. Inheritance of glyphosate‐resistance in H. glaucum is non‐Mendelian. Individual F2 progenies have variable numbers of EPSPS gene copies, some higher than the resistant parent.