| Introduction of telocentric chromosome of Chinese Spring
wheat into Emmer wheat* M. OKAMOTO Curtis Hall, Univ. of-Missouri, Columbia, Mossouri, U.S.A. In spite of repeated trials of many workers, monosomics of emmer wheats have not been obtained except monosomic 6A (VI) of Ld 222, a variety of durum wheat (late John Longwell, Jr., unpublished). Apparently the cells from which one whole chromosome is deficient are rarely or never transmitted, either through the male or the female. For some purposes, telocentric chromosomes would be fully as useful as monosomes. The loss of only one arm of a chromosome should, in many cases, be tolerated without serious deleterious effect. Trials are now being made to introduce telocentrics for the chromosomes of the A and B genomes of Chinese Spring wheat into emmer wheats. Plants carrying the telocentrics were crossed by emmer, and repeated backcrosses are in progress in order to eliminate the D-genome chromosomes. Plants with a telocentric for the long arm (carrying Q) of chromosome 5A (IX) and one normal 5A, and free from D-genome univalents have already been obtained. These plants were just as fertile as the parent emmer wheat. The telocentrics that can be obtained in tetraploid wheat will be used for studies on the nature of the differentiation of the A genome. |
| * This work was supported in part by a grant from the National Science Foundation to Dr. E. R. Sears. |