The phylogenesis of protein ?-amylase inhibitors from wheat seed and the speciation of polyploid wheats

Abstract

Protein α-amylase inhibitors extracted with water from seeds of a number of Triticum and Aegilops species were characterized according to their molecular weights and action specificities towards human salivary and Tenebrio molitor L. α-amylases. Four inhibitor peaks, with molecular weights 60000, 44000, 22000 and 11000, active towards the two amylases have been detected. Another inhibitor peak with molecular weight 11000, only active towards the insect α-amylase, has been found in several species tested. Triticum urartu showed only the 22000 inhibitor peak, while other diploid Triticum species did not exhibit any inhibitory activity. All the diploid Aegilops species tested contained α-amylase inhibitors and the inhibitor patterns differed greatly even for closely related species. In general, tetraploid Triticum species (turgidun and timopheevi) exhibited amylase inhibitor patterns of higher complexity than diploid Triticum and Aegilops species. The relationships existing among the amylase inhibitor patterns of the Triticinae species tested are consistent with the hypothesis of the polyphyletic origin of tetraploid wheats by Sarkar and Stebbins (1956) and suggest that the amylase inhibitors from diploid species all derive from common ancestral genes.