II.24. Hordein mutants for barley Hrd loci.
V.P Netsvetaev (l) and A.A. Sozinov, Laboratory of Plant Biochemical Genetics, Institute of General Genetics A.S. U.S.S.R., Moscow 117809, U.S.S.R.
(1)Laboratory of Biochemical Genetics, All-Union Institute of Plant Breeding and Genetics, 270036 Odessa, U.S.S.R.
The barley varieties Donetsky 4 and Uzhniy, which had been taken as genetically pure in respect to studying factors, were used to produce mutations. Barley seeds were treated with 0.2% EMS for 18 hours at room temperature. Sowing was carried out after washing and drying.
Hordein of single or half-seeds was analysed by electrophoresis from each M1 plant, to select mutants. The starch gel electrophoresis was performed at pH 3.1 according to Sozinov and Poperelya procedure (1974).
1287 of single or half-seeds of var. Donetsky 4 and 657 of single or half-seeds of var. Uzhniy were tested. 22 and 7 seeds were found with changed hordein, respectively. At first stage whole seeds were used for electrophoresis and because of this a lot of mutants were lost. Hence, it would be more suitable to analyse just a part of an individual seed. The other part of seed with embryo can be sown for receiving the progeny, if it is necessary.
Some results of mutagen treatment of the var. Donetsky 4 are summarized here. Fig. 1 shows the inheritable change of X-polypeptide mobility in HRD A zone, controlled by locus Hrd A. The mutant VN 1 has the changed x-polypeptide in comparison with the initial X-polypeptide (the lower part of the faster moving component of hordein A of var. Donetsky 4). Heterozygous plant has 3 classes of seeds with hordein variants in ratio 1:2:1, X2=1.90 (21:53:19). The class I has hordein quite similar to Donetsky 4 (X-polypeptide is present; x-polypeptide is absent), the class II is presented with hordein of initial (X) and changed (x) polypeptides simultaneously, the class III - with hordein closely similar to VN 1 line (x-polypeptide is present and X polypeptide is absent). Hence, the components X and x are products of different alleles of a single gene. The similar picture was observed when analysing a hybrid progeny of VN 2 line. This line has phenotype identical to VN 1, but it was selected from other mutant family.
When analyzing M2 seeds some changes were found. They are shown at Fig. 2. The observed reduction of polypeptide mobility is controlled by locus Hrd F (Netsvetaev and Sozinov, 1982) (initial - Y; changed - y). Types, in which the less-mobile component was absent at the A hordein zone have been observed with high frequency, about a half of all changes (zone of hordein A is pointed out by winding arrow in Fig. 2). Approximately the same frequency was obtained for changes shown in Fig. 1. No changes in hordein B were obtained. The same for the intermediate-moving components of A-hordeins was observed.
Some hordein changes of var. Uzhniy mutants affected different components of hordein A.
It is known, that each hordein locus Hrd A (=Hor 1) and Hrd B (=Hor 2) controls synthesis of more than one polypeptide (block of components) (Sozinov et al., 1978; Shewry et al., 1978; Doll and Brown, 1979; Pomortsev et al., 1983). In 1982 we tested 1651 F2 seeds, 12200 F3 seeds and 2312 F-- seeds in different cross combinations, but no recombinant classes were found in proteins controlled by the same locus. The block of hordein components appeared to be a stable unit of inheritance. In the light of these data the search and the study of hordein mutants shows us that hordein loci are probably polygenous.
References:
Doll, H. and A.H.D. Brown. 1979. Hordein variation in wild (Hordeum spontaneum) and cultivated (H. vulgare) barley. Can. J. Genet. Cytol. 21:391-404.
Netsvetaev, V.P, and A.A. Sozinov. 1982. Linkage studies of genes Gle1 and Hrd F in barley chromosome 5. BGN 12:13-18.
Pomortsev, A.A., V.P. Netsvetaev, F.A. Poperelya, A.A. Sozinov. 1983. Identification of the sixth locus controlling synthesis of hordein in winter barley. Doklady VASKHNIL. No. 1:7-9.
Shewry, P.R., H.M. Pratt, R.A. Finch and B.J. Miflin. 1978. Genetic analysis of hordein polypeptides from single seeds of barley. Heredity 40:463-466.
Sozinov, A.A. and F.A. Poperelya. 1974. Vertical starch-gel electrophoretie method of protein separation. Information Bulletin COMECON 1:135-144.
Sozinov, A.A., V.P. Netsvetaev, E.M. Grigoryan and I.S. Obraztsov. 1978.
Mapping of Hrd loci in barley (H. vulgare L. emend, Vav. et Bacht.). Genetika
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