
%0 Journal Article
%A Tardif, FJ 
%A Preston, C 
%A Holtum, JAM 
%A Powles, SB 
%T Resistance to Acetyl-Coenzyme a Carboxylase-Inhibiting Herbicides Endowed by a Single Major Gene Encoding a Resistant Target Site in a Biotype of <I>Lolium rigidum</I>
%J Functional Plant Biology
%D 1996/02/01
%V 23
%N 1
%P 15-23
%K 
%R https://doi.org/10.1071/PP9960015
%U https://www.publish.csiro.au/paper/PP9960015 
%X The mechanism and mode of inheritance of resistance to acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides was investigated in a biotype of Lolium rigidum that has evolved resistance following selection with diclofop-methyl for 10 consecutive years. ACCase extracted from the resistant biotype is > 6.9 times more resistant to inhibition by diclofop than enzyme from a susceptible biotype. Similar or greater levels of resistance were found to other related herbicides. There is no difference in absorption or metabolism of diclofop-methyl or haloxyfop-methyl between the resistant and susceptible biotypes, hence differential absorption or metabolism of these herbicides does not contribute to resistance. F1 families from reciprocal crosses between the resistant biotype and a susceptible biotype respond similarly to the herbicide and are nearly as resistant as the resistant parent, indicating that the resistance trait is nuclearly located and has incomplete dominance over susceptibility. F2 families treated with 26 and 208 g ai ha-1 of haloxyfop-ethoxyethyl reveal only two phenotypes: resistant plants showing no injury and susceptible plants showing no growth. At both rates of haloxyfop-ethoxyethyl, the segregation of resistance to susceptibility follows a ratio of 3:1 (R:S) that fits the predicted ratio for a single nuclear gene with high dominance. From the F1 and F2 data, it is concluded that resistance to haloxyfop in this resistant biotype of L. rigidum is inherited as a single nuclear incompletely dominant gene coding for a resistant form of the target enzyme ACCase. 
