Randhawa Harpinder S, Mutti Jasdeep S, Kidwell Kim, Morris Craig F, Chen Xianming, Gill Kulvinder S
Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA.
PLoS One. 2009 Jun 1;4(6):e5752. doi: 10.1371/journal.pone.0005752.
A marker-assisted background selection (MABS)-based gene introgression approach in wheat (Triticum aestivum L.) was optimized, where 97% or more of a recurrent parent genome (RPG) can be recovered in just two backcross (BC) generations. A four-step MABS method was developed based on 'Plabsim' computer simulations and wheat genome structure information. During empirical optimization of this method, double recombinants around the target gene were selected in a step-wise fashion during the two BC cycles followed by selection for recurrent parent genotype on non-carrier chromosomes. The average spacing between carrier chromosome markers was <4 cM. For non-carrier chromosome markers that flanked each of the 48 wheat gene-rich regions, this distance was approximately 12 cM. Employed to introgress seedling stripe rust (Puccinia striiformis f. sp. tritici) resistance gene Yr15 into the spring wheat cultivar 'Zak', marker analysis of 2,187 backcross-derived progeny resulted in the recovery of a BC(2)F(2ratio3) plant with 97% of the recurrent parent genome. In contrast, only 82% of the recurrent parent genome was recovered in phenotypically selected BC(4)F(7) plants developed without MABS. Field evaluation results from 17 locations indicated that the MABS-derived line was either equal or superior to the recurrent parent for the tested agronomic characteristics. Based on these results, MABS is recommended as a strategy for rapidly introgressing a targeted gene into a wheat genotype in just two backcross generations while recovering 97% or more of the recurrent parent genotype.
对基于标记辅助背景选择（MABS）的小麦（普通小麦）基因渐渗方法进行了优化，通过该方法，只需两个回交（BC）世代就能找回97%或更多的轮回亲本基因组（RPG）。基于“Plabsim”计算机模拟和小麦基因组结构信息，开发了一种四步MABS方法。在对该方法进行实证优化期间，在两个BC轮回中逐步选择目标基因周围的双重组体，随后在非携带染色体上选择轮回亲本基因型。携带染色体标记之间的平均间距小于4厘摩。对于位于48个小麦基因丰富区域两侧的非携带染色体标记，该距离约为12厘摩。利用该方法将抗小麦条锈病（条形柄锈菌小麦专化型）基因Yr15导入春小麦品种“Zak”，对2187个回交衍生后代进行标记分析，获得了一个具有97%轮回亲本基因组的BC(2)F(2ratio3)植株。相比之下，在未使用MABS的情况下通过表型选择培育的BC(4)F(7)植株中，仅找回了82%的轮回亲本基因组。来自17个地点的田间评估结果表明，MABS衍生系在测试的农艺性状方面与轮回亲本相当或更优。基于这些结果，建议将MABS作为一种策略，在仅两个回交世代内将目标基因快速渐渗到小麦基因型中，同时找回97%或更多的轮回亲本基因型。
