Chromosome engineering in wheat

Three methods have been developed for the transfer of genetic material to wheat chromosomes from alien chromosomes: (i) Use of ionizing radiation to translocate an alien segment. (ii) Induction of homoeologous pairing, which may be followed by crossing over. This is the easiest and usually the most effective method, provided the alien chromosome is sufficiently closely related to one of its wheat homoeologues that frequent pairing can occur. (iii) Exploitation of the tendency of univalent chromosomes to misdivide. Telocentrics resulting from simultaneous misdivision of two univalents have recently been shown to unite and to produce a new chromosome having one arm from each of the univalents.E. R. SEARS, U.S. Department of Agriculture and Agronomy Department, University of Missouri, Columbia, Missouri