The American geneticist, E. R. Sears, was the founder of wheat chromosome engineering.He established the monosomic series of common wheat, which greatly facilitated cytogenetic analysis of wheat. However, problems of univalent shift and labor involved in chromosome counting have limited the common usage of these materials. To circumvent these problems, I developed an alternative set of monosomic lines, in which the presence of the univalent chromosome was indicated by the production of blue pigmentation in the aleurone tissue of seeds. The gene(s) responsible for the blue pigmentation were carried on a short chromosomal fragment of Agropyron elongatum. This chromosomal fragment has been transferred to the different chromosomes of common wheat using radiation induced translocation. On the spike derived from a blue grained monosomic wheat (2 n =41, the univalent chromosome carries the gene for the blue pigmentation), four types of seeds are produced. The deep blue seed has 42 chromosomes, the medium blue and light blue seed has 41 chromosomes, and the white seed has 40 chromosomes. The monosomic genotype is easily identified based on the color of the seed, without the use of microscope. So far, blue grained monosomic lines have peoduced 11 of the 21 different wheat chromosomes. In the course of propagating the blue grained monosomics, I found that the fertility of the nullisomic lines (2 n =40, represented by white seeds) could be improved by continued selfing and reselection. Using the resulted self fertile nullisomic lines, I established an efficient procedure for producing alien substitution lines of wheat. The utilization of the blue grained monosomic lines and the self fertile nullisomic lines may facilitate chromosome engineering studies in wheat.
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