Rustgi Sachin, Matanguihan Janet, Mejías Jaime H, Gemini Richa, Brew-Appiah Rhoda A T, Wen Nuan, Osorio Claudia, Ankrah Nii, Murphy Kevin M, von Wettstein Diter
Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America.
Department of Crop & Soil Sciences, Washington State University, Pullman, Washington, United States of America; Instituto de Investigaciones Agropecuarias INIA, Vilcún, Chile.
PLoS One. 2014 Jun 26;9(6):e100998. doi: 10.1371/journal.pone.0100998. eCollection 2014.
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.
咪唑啉酮（IMI）除草剂的广泛应用对大麦产量产生了重大影响，导致过去二十年来其种植面积持续下降。解决这一问题的一个可能办法是将“Bob”大麦乙酰羟酸合酶（AHAS）基因中最近鉴定出的突变所赋予的IMI抗性转移到其他食用、饲料用和麦芽用大麦品种中。我们致力于将IMI抗性转移到适应美国太平洋西北地区（PNW）的大麦品种上，因为该地区占美国大麦种植农用地的约23%（33.5万公顷）。为了有效地培育抗IMI的品种，我们使用61个微卫星标记研究了来自PNW的13个二棱春大麦品种/育种系之间的遗传多样性，并选择了六个与“Bob”AHAS突变体具有中等至高遗传差异的大麦基因型。所选的六个基因型与AHAS突变体进行了29 - 53次杂交，获得了358 - 471粒F1种子。为了明智地选择以恢复受体亲本基因组，确定了AHAS基因 的遗传位置并评估了其遗传特性。对大小从2158 - 2846个个体不等的大型F2群体进行了除草剂抗性和幼苗活力评估。根据结果，对每个杂交组合中六个最具活力的F2基因型的F3株系进行了遗传背景评估。观察到载体染色体上受体亲本基因组的恢复率在20% - 90%之间。努力确定区分突变等位基因杂合子和纯合子的除草剂临界剂量。结果表明，突变体在高达田间推荐剂量10倍的除草剂条件下仍能存活，8倍和10倍除草剂剂量可区分两种AHAS突变基因型。最后，讨论了本研究对维持PNW地区大麦产量的意义。
