Development and Chromosome Characterization of Wheat Aneuploids.

Development of aneuploids in wheat is traditionally conducted through crossing and backcrossing, followed by selfing for several generations to produce genetically stable progeny. In this study, we developed wheat aneuploids using the wheat-maize pollen doubled haploid (DH) method.  A cross of 08-47-50/Crocus was made in 2011. Crocus is a wheat line (AABBDD) with three crossability genes (kr1kr2kr3), while 08-47-50 is a partial amphiploid (AABBEE) with resistance to leaf rust, stem rust, powdery mildew and Fusarium head blight (FHB). F₁ plants were used for producing doubled haploids. Two hundred and eighty-eight embryos were recovered from 15,186 florets pollinated with corn pollen. Thirty-two plantlets were obtained from these embryos. Finally, eight stable doubled haploid lines were obtained with chromosome numbers ranging from 42 to 48. The results of disease evaluation showed that the line DH-Cro50-5 was resistant to FHB and that the line DH-Cro50-7 was highly resistant to powdery mildew similar to the amphiploid parent. The remaining lines showed resistance to leaf rust, stripe rust and/or Ug99 stem rust races. Chromosome characterization of these DH lines was conducted using genomic in situ hybridization. Preliminary results revealed that the line DH Cro50-2 had 42 chromosomes with a terminal translocation.  The results of this study indicate that application of DH technology can save considerable time in the development of aneuploids in wheat compared to traditional methods. Because the new aneuploid lines are doubled haploids, they can be used directly as new sources of disease resistance in wheat breeding programs.