THE GENETIC-CONTROL AND TISSUE-SPECIFICITY OF ESTERASE ISOZYMES IN HEXAPLOID WHEAT

A comparative genetic analysis of esterase (E.C.3.1.1.1) isozymes of wheat cultivar 'Chinese Spring' in endosperm, embryo, coleoptile, leaf and root tissues revealed eight sets of isozymes characterised by different tissue specificities, pI ranges and the chromosomal locations of their controlling genes. This data was considered together with previously published work, resulting in a proposed rationalization of nine sets of wheat esterase isozymes. Although this classification included two sets of isozymes controlled by genes on the short arms of homoeologous group 3 chromosomes and three sets on the long arms of the same chromosomes, for which no recombination evidence of genetic distinctness has been obtained among either group, it is argued that the different characteristics of the various sets warrant retention of separate set nomenclatures. Previously unreported esterase genes include Est-9, a low pI, monomeric, embryo-specific group with controlling genes on chromosomes 3BS and 3DS and two further members of Est-1, Est-H1 in Hordeum vulgare and Est-S-l 1 in Aegilops longissima.