Genetic control of triosephosphate isomerase isoenzymes in wheat and rye

Summary The patterns of chloroplastic and cytosolic isoenzymes of triosephosphate isomerase were analysed by immunoblotting in leaves of rye, wheat, and some species of Aegilops or Agropyrum. While rye contained solely one chloroplastic and one cytosolic isoenzyme, wheat had a much more complex pattern which can be explained by the presence of three genomes in 6 x wheats (AABBDD) with distinct triosephosphate isomerase genes that provided different subunit species for the dimeric isoenzyme molecules. The 6 × wheats contained five, the 4 × wheats three, and the 2 × wheats only one chloroplastic isoenzyme band. The isoenzyme patterns were in accordance with a potential origin of one of the three chloroplastic triosephosphate isomerase genes of 6 × wheats from an Aegilops ancestor. The descent of the other two genes was, however, not in accordance with common contentions on the general evolution of cultural wheats. In the reciprocal intergeneric hybrids Secalotricum and Triticale both the chloroplastic and the cytosolic isoenzyme patterns of rye and wheat were biparentally inherited, indicating that both isoenzymes were controlled by nuclear genes. When monitored by immunoblotting the chloroplastic triosephosphate isomerase isoenzymes may provide useful genetic markers.