II.35 Inheritance of high lysine endosperms in barley.
D.A. Somers, A.J, Lejeune, and A. Kleinhofs, Department of Agronomy and Soils and Program in Genetics, Washington State University, Pullman, Washington 99163, U,S.A.
The nature of the endosperm protein characteristics associated with the high lysine content of Hiproly (CI3947) and Risø Mutant 1508, as described by Munck (1972) and Ingversen et al. (1973), suggested that two different recessive genes are involved Tallberg (1973) provided evidence through S.E.M. and electrophoretic studies of the endosperm proteins that the elevated lysine content of the two lines was indeed due to two different genes. Genetic analysis in our laboratory of the cross Mutant 1508/CI3947 provided conclusive evidence that the two genes for increased lysine content are independent and non-allelic (Muench et al. 1975, 1976).
The results of analysis of 31 out of 210 F3 lines from the cross mentioned showed a range in lysine content of 2.78-6.42 g lysine/100 g protein. It was postulated that the line D-129 exhibiting 6.42 g lysine/ 100 g protein represents a double recessive homozygote (Muench et al. 1975, 1976).
During the summer of 1975 F3 seeds were planted in rows and the F4 seed harvested in bulk from each row. Using barley flours of known protein and lysine content as standards, preliminary analysis was conducted on 100 of the 210 lines using modified Biuret (Johnson and Cranez, 1971) and Ninhydrin (Beckwith et al. 1975) assays for protein and lysine, respectively. The range for the 100 lines analyzed was 3.37-5.90 g lysine/100 g protein, and it was found using the Ninhydrin/Biuret assay that line D-129 contained 5.9 g lysine/100 g protein this season. This figure was confirmed by amino acid analysis. Five other lines exhibited high lysine content similar to D-129 and it is surmised that they represent homozygotes for both high lysine genes as well. Homozygosity will be checked by a single seed assay for lysine and protein presently being developed.
Based on the two recessive gene hypothesis (Muench et al., 1976; Munck, 1972) the lysine content of F3 and F4 generation lines will depend on the genotype of the individual F2 parent plants. Thus, the expected frequency of double recessive homozygotes would be 1/16 or about 13 out of 210 lines. The detection of six homozygous phenotypes from approximately 100 lines appears to be in good agreement with the present hypothesis. Further analysis of all F4 lines available from the original cross should elucidate the mode of inheritance of high lysine in barley endosperms.
References:
Beckwith, A.C., J.W. Paulis, and J.S. Wall, 1975. Direct estimation of lysine in corn meals by the Ninhydrin color reaction. Agricultural and Food Chemistry 23: 194.
Ingversen, J., B. Køie, and H. Doll, 1973 Induced seed protein mutant of barley. Experientia 29: 1151-1152.
Johnson, R.M. and C.E. Cranez, 1971. Rapid biuret method for protien content in grains. American Association of Cereal Chemists, Inc., St. Paul.
Muench, S.R., A.J. Lejeune, R.A. Nilan, and A. Kleinhofs, 1975. Evidence for two independent high lysine genes in barley. In Barley Genetics Newsletter 5:31.
Muench, S.R., A,J. Lejeune, R.A. Nilan, and A. Kleinhofs, 1976. Evidence for two independent high lysine genes in barley. Crop Science (In Press).
Munck, L., 1972. Improvement of nutritional value in cereals. Hereditas 72: 1-128.
Tallberg, A., 1973. Ultrastructure and protein composition in high lysine barley mutant. Hereditas 75: 195-200.