title: Assessment of genetic diversity among barley cultivars and breeding lines adapted to the US Pacific Northwest, and its implications in breeding barley for imidazolinone-resistance.
abstract: Extensive application of imidazolinone (IMI) herbicides had a significant impact on barley productivity contributing to a continuous decline in its acreage over the last two decades. A possible solution to this problem is to transfer IMI-resistance from a recently characterized mutation in the 'Bob' barley AHAS (acetohydroxy acid synthase) gene to other food, feed and malting barley cultivars. We focused our efforts on transferring IMI-resistance to barley varieties adapted to the US Pacific Northwest (PNW), since it comprises ∼23% (335,000 ha) of the US agricultural land under barley production. To effectively breed for IMI-resistance, we studied the genetic diversity among 13 two-rowed spring barley cultivars/breeding-lines from the PNW using 61 microsatellite markers, and selected six barley genotypes that showed medium to high genetic dissimilarity with the 'Bob' AHAS mutant. The six selected genotypes were used to make 29-53 crosses with the AHAS mutant and a range of 358-471 F1 seeds were obtained. To make informed selection for the recovery of the recipient parent genome, the genetic location of the AHAS gene was determined and its genetic nature assessed. Large F2 populations ranging in size from 2158-2846 individuals were evaluated for herbicide resistance and seedling vigor. Based on the results, F3 lines from the six most vigorous F2 genotypes per cross combination were evaluated for their genetic background. A range of 20%-90% recovery of the recipient parent genome for the carrier chromosome was observed. An effort was made to determine the critical dose of herbicide to distinguish between heterozygotes and homozygotes for the mutant allele. Results suggested that the mutant can survive up to the 10× field recommended dose of herbicide, and the 8× and 10× herbicide doses can distinguish between the two AHAS mutant genotypes. Finally, implications of this research in sustaining barley productivity in the PNW are discussed.
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Sachin
authors: S
authors: Rustgi
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Janet
authors: J
authors: Matanguihan
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America; Instituto de Investigaciones Agropecuarias INIA, Vilcún, Chile.
authors: Jaime H
authors: JH
authors: Mejías
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Richa
authors: R
authors: Gemini
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Rhoda A T
authors: RA
authors: Brew-Appiah
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Nuan
authors: N
authors: Wen
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Claudia
authors: C
authors: Osorio
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Nii
authors: N
authors: Ankrah
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
authors: Kevin M
authors: KM
authors: Murphy
authors: Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America; School of Molecular Biosciences, Washington State University, Pullman, Washington, United States of America; Centre for Reproductive Biology, Washington State University, Pullman, Washington, United States of America.
authors: Diter
authors: D
authors: von Wettstein
mesh_terms: D000095:Acetolactate Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000220:Adaptation, Biological; D001947:Breeding; D002874:Chromosome Mapping; D016000:Cluster Analysis; D003433:Crosses, Genetic; D008040:Genetic Linkage; D014644:Genetic Variation; D005838:Genotype; D053209:Herbicide Resistance / Q000235:genetics*; D001467:Hordeum / Q000187:drug effects* / Q000235:genetics*; D018895:Microsatellite Repeats; D015205:Northwestern United States; D011110:Polymorphism, Genetic; D054730:Protein Interaction Domains and Motifs
chemical_list: D000095:Acetolactate Synthase