| Structural relationships between non-homologous chromosomes
M. OKAMOTO and E. R. SEARS University of Missouri, Columbia, Missouri, U.S.A. When haploid plants of Chinese Spring wheat were pollinated by normal Chinese, 15 reciprocal translocations were obtained. Since these translocations are presumably the result of crossing over between homologous regions of non-homologous chromosomes in the haploid, identification of the chromosomes involved in the translocations will show which chromosomes of wheat are structurally related. The analysis is of particular interest in connection with the homoeologous groups which have been identified in hexaploid wheat. The analysis is being made by crossing each translocation line onto the 21 different nullisomics or monosomics. If the chromosome in question is not included in the translocation, the monosomic offspring have 18II+4+1I or 18II+(4)+1I. If the chromosome is included in the translocation, the monosomic offspring have 19II+3. Eight translocations have been fully analyzed and two partially analyzed, with the following results;
Of the eight fully analyzed translocations, only two involve the same chromosomes (VI and XIX). Of the seven different translocations, three involve homoeologous chromosomes, and four involve non-homoelogous ones. Chromosome VI is involved in four of the ten translocations. |