Evolution and diversity of PAPhy_a phytase in the genepool of wheat (Triticum aestivum L., Poaceae)

Abstract

Higher phytase activity in food and feedstuffs is desirable in order to counter the antinutritional effects of phytate. The most promising platform where this might be achieved through plant breeding is wheat and its Triticeae relatives. They already accumulate notable amounts of phytase in the grains and higher expression of the responsible PAPhy_a gene can increase the activity further. Here we provide a survey of the genetic diversity of PAPhy_a in wild and extant relatives of wheat. Fifty sequences of the structural gene were obtained from 34 samples representing 21 species or subspecies. A phylogenetic tree is presented, demonstrating that the three gene copies in hexaploid wheat have been inherited from its diploid ancestors. This finding is not only relevant for applied research, it also provides further evidence regarding the origin of the genomes in polyploid wheat. T. urartu Tumanian ex Gandilyan and Ae. tauschii Coss. are confirmed as donors of the A and D genomes, respectively, and the hypothesis of a common origin (Ae. speltoides Tausch) of the B and G genomes is supported. The survey suggests that the allele variation available for breeding is increased by the inclusion of the closest relatives of wheat. This effort should benefit greatly from molecular methods because specimens of the same species may have either novel- or alleles-identical to those of wheat.