Abstract
Agropyron cristatum, a wild relative of wheat, possesses many elite genes for enlarging the genetic diversity of wheat and improving wheat yield. Our previous study confirmed that the A. cristatum chromosome 1P carries alien genes that reduce plant height and leaf size. Here, we developed T1AL.1PS and T1AS.1PL Robertsonian translocations (RobTs) by using breakage-fusion mechanism based on wheat-A. cristatum 1P(1A) substitution line. Combining molecular markers and cytological analysis, we identified 16 spontaneous Robertsonian translocation lines from 911 F2 individuals with a translocation frequency up to 1.7%. Fluorescence in situ hybridization (FISH) was applied to detect the fusion structures of the centromeres in wheat and A. cristatum chromosomes. Re-sequencing results indicated the junkpoint at the physical position of Triticum aestivum chr1A 212Mb and A. cristatum chr1P 230Mb. Genomic in situ hybridization (GISH) results of pollen mother cells showed that the produced translocation lines could form stable ring bivalent. The genetic analysis showed that introducing 1PS translocation fragment into wheat could increase the number of fertile tillers, grain number per spike and grain weight, and reduce flag leaf area of wheat without yield penalty. However, introducing 1PL translocation fragment into wheat reduce significantly flag leaf area and plant height with adverse effect on the yield components. Altogether, a high-efficient method for producing the spontaneous translocation lines by combining the molecular marker and cytogenetics technology were recommended. The pre-breeding of two spontaneous RobTs T1AL.1PS and T1AS.1PL pave the way for the wheat architecture improvement.