Linkage Among Glume and AWN Characters in Tetraploid Wheats

Linkage relationships among glume hairiness, glume color, awn color and beak-shape in nine intra-and five inter-specific crosses qf tetraploid wheats have been studied. Pleiotropic complex noted in T. durum cross for glume hairiness and awn color has been found to have resolved in other crosses with over a various separation of loci ranging from 2–37% to 37–24% cross-over values, in extreme cases recombination values of linked loci show anomalous values exceeding 50%, possibly due to centromeric affinities among parental chromosomal sets as reported in mice and cotton. Constancy as also inconstancy in linkage among these characters and anomalous situations such as (i) reversal of recombination phases (coupling⇄repulsion), (ii) cross-over values more than 50%, (iii) alterations in the relative cross-over intervals etc. have been worked out. Reasons for such anomalies suggested to be due to differences in the genetic constitutions of individual characters, reversal of dominance have been discussed.