II. 28. Localization on barley chromosome 4 of genes coding for beta-amylase (Bmyl) and protein Z (Pazl).
Gunnar Nielsen, Hanne Johansen and Jens Jensen, Agricultural Research Department, Risø National Laboratory, DK-4000 Roskilde, Denmark. Jørn Hejgaard, Department of Biochemistry and Nutrition, Technical University of Denmark, DK-2800 Lyngby, Denmark.
A gene coding for protein Z, a major endosperm albumin (Hejgaard 1982), has been shown to be located on chromosome 4 by means of a set of wheat-barley addition lines obtained from Dr. A.K.M.R. Islam, Adelaide. Detection of the gene product could easily be made by rocket immunoelectrophoresis into monospecific antibodies towards protein Z, as no cross-reacting proteins are present in wheat. Protein Z is relatively rich in lysine, the protein is present in increased amounts in some high-lysine barleys, and it responds to N-fertilization almost like the true storage proteins (Hejgaard and Boisen 1980). In many respects, protein Z seems to be "related to" beta-amylase which originates from a locus on the same chromosome (Powling et al. 1981). For the "protein albumin Z" we propose the locus designation Pazl. For the B-amylase we previously suggested Baml (Nielsen 1982). However, as Bam refers to a restriction enzyme we propose to change the notation for the beta-amylase locus to Bmy1. We prefer a designation different from Amy which has been used for an alpha-amylase locus (Nielsen and Frydenberg 19 74).
A series of crosses were mate in order to study the linkage relationship of Bmyl and Pazl with other chromosome 4 genes. The banding pattern of beta-amylase and protein Z were scored after polyacrylamide gel electrophoresis and subsequent protein staining of extracts from the ungerminated nonembryo half of the F2 kernels. The embryo half was grown in a greenhouse to be scored for various morphological characters conditioned by marker genes.
The results from the crosses are illustrated by the partial linkage map shown in Fig. 1. Rather close linkage was found between Paxl, ari-c and gl4 and also between Bmyl and yh, whereas these two groups of loci are only loosely linked. Further, our data indicate that loci f9 and K, which are located in one end of the chromosome 4 linkage map, were far away from the loci shown in Fig. 1.
The data reported by Jørgensen (1977) suggested that yh is located in the other end of chromosome 4 that carries f9 and K. Therefore, the Pazl locus seems to be located in the middle part of the chromosome 4 linkage map, and the yh locus seems to be located distally in the chromosome arm not carrying f9.
References:
Hejgaard, J. 1982. Purification and properties of protein Z - a major albumin of barley endosperm. Physiol. Plant. 54:174-182.
Hejgaard, J. and S. Boisen. 1980. High-lysine proteins in Hiproly barley breeding: Identification, nutritional significance and new screening methods. Hereditas 93:311-320.
Jørgensen, J. H. 1977. Location of the ml-o locus on barley chromosome 4. In: Induced Mutations Against Plant Diseases. L9EA, Vienna. p. 533-549.
Nielsen, G. 1982. Supplementary and new evidence on the location of five enzyme loci on barley chromosomes. BGN 12:68-69.
Nielsen, G. and 0. Frydenberg. 1974. Linkage between the loci Amyl (alpha-amylase), o (orange lemma), and Xn (Xantha seedling). BGN 4:53-54.
Powling, A., A.K.M.R. Islam and K. W. Shepherd. 1981. Isozymes in wheatbarley hybrid derivative lines. Biochem. Genet. 19:237-254.
