Characterization of imadazolinone resistant spring wheat (Triticum aestivum L.)

Abstract

Spring wheat (Triticum aestivum L.) plants resistant to imidazolinone herbicides were identified following seed mutagenesis. Six M3:6 homozygous lines were selected for genetic study. The lines were designated as TealIMI lines 1A, 9A, 10A, 11A, 15A, and 16A. Resistant line BW755 carries a previously characterized partially dominant resistance gene (FS-4). Based on analysis of F1, F2, backcross (BC)1F1 and F2:3 generations, resistance in lines 1A, 9A, 10A, 11A, and 16A is a partially dominant trait inherited as a single nuclear gene. Resistance in TealIMI 15A is dominant and is inherited as two independent nuclear-coded genes. Evaluation of F2 and F2:3 generations resulting from all possible inter-crosses between resistant lines indicated that resistance genes in lines 1A, 9A, 10A, and 16A are allelic to FS-4. No segregation was observed in F2 populations resulting from the cross 15A/BW755, indicating that one of the two resistance genes in 15A is allelic to FS-4. All crosses between resistant lines and 11A produced segregating F2 populations suggesting the presence of a unique resistance gene in 11A. Segregating F2 populations resulting from the cross 11A/15A gave a good fit to a three locus model, indicating that the second resistance gene in 15A is not allelic to that found in 11A. The resistance genes were named based on the recommended rules for gene symbolization in wheat. The FS-4 allele was renamed Imi1. Line 15A carries resistance genes Imi1 and Imi3 whereas line 11A carries Imi2.