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Title: Rapid and Targeted Introgression of Genes into Popular Cultivars Using Marker-Assisted Background Selection

Author
item RANDHAWA, HARPINDER - WASHINGTON STATE UNIV
item MUTTI, JASDEEP - WASHINGTON STATE UNIV
item KIDWELL, KIM - WASHINGTON STATE UNIV
item Morris, Craig
item Chen, Xianming
item GILL, KULVINDER - WASHINGTON STATE UNIV

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2009
Publication Date: 6/1/2009
Citation: Randhawa, H.S., Mutti, J.S., Kidwell, K.K., Morris, C.F., Chen, X., Gill, K.S. 2009. Rapid and Targeted Introgression of Genes into Popular Cultivars Using Marker-Assisted Background Selection. PLoS One 4(6):e5752

Interpretive Summary: We have optimized a marker-assisted background selection (MABS)-based gene introgression approach in wheat where 97% or more of a recurrent parent genome can be recovered in just two backcrosses (BCs). 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 on priority in a step-wise fashion during the two BC cycles followed by selection for the non-carrier chromosomes. We employed the approach to introgress the Yr15 stripe rust resistance gene into cultivar ‘Zak’. With 2,187 markers, we identified a BC2F2:3 plant that carried 97% of the recurrent parent genome. In contrast, phenotypically selected BC4F7 plants without the MABS recovered only 82% of the recurrent parent genome. Field evaluation at 17 locations showed that the MABS derived line to be either equal or superior to the recurrent parent. These results, show that the MABS method is efficient to recover desired level of recurrent parent genome.

Technical Abstract: We have optimized a marker-assisted background selection (MABS)-based gene introgression approach in wheat where 97% or more of a recurrent parent genome can be recovered in just two backcrosses (BCs). 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 on priority in a step-wise fashion during the two BC cycles followed by selection for the non-carrier chromosomes. The average spacing among the carrier chromosome markers was <4 cM. Flanking each of 48 wheat gene-rich regions, the same number for non-carrier chromosome markers was ~12 cM. Employed to introgress the Yr15 gene into cultivar ‘Zak’, marker analysis of 2,187 identified a BC2F2:3 plant that carried 97% of the recurrent parent genome, while phenotypically selected BC4F7 plants without the MABS recovered only 82% of the recurrent parent genome. Field evaluation at 17 locations showed that the MABS derived line to be either equal or superior to the recurrent parent. Based on these results, an MABS method was proposed for wheat using which any desired level of recurrent parent genome recovery is possible in just two backcrosses.