THE EVOLUTION OF THE PHENOL COLOUR REACTION GENE IN WHEAT

Abstract

Phenol reaction of the seeds in a number of varieties of the diploid species having AA, BB, DD genomes and the tetraploid and hexaploid species having the genomic constitution AABB and AABBDD has been studied. Among the diploid species all the six varieties of T. monococcum (AA) and two of T. boeoticum (AA) have shown black reaction. All the varieties of Ae. speltoides (BB) and Ae. squarrosa (DD) have shown white reaction. A variety of reactions ranging from black, brown to white has been shown by the varieties of tetraploid and hexaploid wheats. It has been concluded that ‘A’ genome is. the source of origin of the phenol reaction gene in the emmers and bread wheats. A variety of reactions in the tetraploid and hexaploid levels might have been brought about by mutation and recombinations. Plausible ways of origin of T. zhukovskyi, having supposed genomic constitution AAAABB from T. timopheevi have been discussed in view of the presence of a desynaptic mechanism in the latter and the phenol colour reaction in both of them.