Kahler and Allard (1970) indicated that 3 loci, Est₄, Est₂ and Est₄, for esterase isozymes were tightly lilnked with each other. This was also confirmed by Nielsen and Frydenberg (1971a), and these loci were shown to be located on chromosome 3 by use of trisomics (Nielsen and Frydenberg 1971b). However, in their studies on interrelationships of Est₄ and Est₁ with f₂ for chlorina, Est₁ and Est₄ were somewhat apart from each other, having a 11.5% and 30.9% recombination values with f₂ locus, respectively (Nielsen and Hvid 1976, Nielsen and Hejgaard 1985). The authors aimed to make clear the linkage relationships between these loci for esterase isozymes and some known marker genes on chromosome 3, using F₂ and F₃ hybrids between Smyrna (x_sx_s) and a linkage tester stock of uz - als - cu2- From F₂ data, the linkage relationship between Est₄ and cu₂ was confirmed, but Est₄ was far apart from uz and als. As shown in Table 1, F₃ data supported further these results, showing that the four loci are arranged in the order of uz-als-cu₃-Est₄ (Figure 1). Thus, Est₄ locus (or the gene block of Est₁, Est₂ and Est₄) was known to be located at the terminal of the long arm of chromosome 3.

References:

Konishi et al. (1984) Kahler, A. L. and Allard, R. W. (1970). Genetics of isozyme variants in barley. I. Esterase. Crop Sci. 10:444-448.

Konishi, T., Hayashi, J., Moriya, I. and Takahashi, R. (1984). Inheritance and linkage studies in barley. VII. Location of six new mutant genes on chromosome 3. Ber. Ohara Inst. Landw. Biol., Okayama Univ. 18:251-264.

Nielsen, G. and Frydenberg, 0. (1971a) The inheritance and distribution of esterase isozymes in barley. Barley Genetics 11: 14-22.

Nielsen, G. and Frydenberg, 0. (1971b) Chromosomal localization of the esterase loci Est-1 and Est-2 in barley by means of trisomics. Hereditas 67:152-154.