II. 7. Induction of dwarfing mutations in spring barley.
S.E. Ulrich and A.L. Hodgdon, Department of Agronomy and Soils. Washington State University. Pullman, WA 99164-6420 "R"
Mutation breeding has been an integral part of the Washington State University Barley Improvement Program for many years. Various forms of radiation and chemical mutagens have been used (Nilan, 1981a). Currently sodium azide (NaN3) is the major mutagenic agent used (Nilan, 1981b), and proanthocyanidin-free grain (Ullrich et al., 1984) and semi-dwarfism (Ullrich et al., 1982, Ullrich and Muir, 1984) are the principal characters selected.
Nearly 250 putative dwarf or semi-dwarf mutants induced with sodium azide have been selected in spring barley since 1980. Semi-dwarf mutants are relatively easily induced in barley with sodium azide. Some of the mutants have been of erectoides types, but most selected have not. For example of the 19 putative mutants selected in 1982, 6 were erectoides. However, in general lax-headed semi-dwarf types have been favored in selection due to an advantage of this type agronomically in the Pacific Northwest, U.S.A. A summary of the mutant selection activities since 1980 are presented in Table 1.
Evaluation of putative mutants selected in M2 populations begins in M3 plant rows. Some mutants may be discarded on the basis of obviously poor plant type: for example weak straw, severe sterility and poor tillering. Grain yield, kernel plumpness and in some cases malting quality are evaluated for the rows visually selected. A host of mutations likely occur from the induced mutagenesis process in each mutant selected, some beneficial, but most detrimental, some detectable, others not. The major objective of the project is germplasm enhancement for breeding purposes. The agronomically better mutants (M3 rows selected are advanced to replicated yield trials. The mutants with the most agronomic potential are then tested further and/or are used as parents in the breeding program. These most promising and unique mutants are analyzed genetically. This work has just begun with some crosses made to determine allelism, gene number and gene action and interaction. Eventually mapping of the genes will also be attempted. Therefore, some useful genetic stocks should result as well as enhanced germplasm for breeding purposes.
References:
Nilan, R.A. 1981a. Induced gene and chromosome mutants. Phil. Trans. R. Soc. Lond. B., 292:457-466.
Nilan, R.A. 1981b. Recent advances in barley mutagenesis, p. 823-831• In Barley genetics IV. Proc. fourth int’1. barley genet. symp. Edinburgh Univ. Press, Edinburgh.
Ullrich, S.E., P.A. Nilan and B. Bacaltchuk. 1982. Evaluation and genetic analysis of semi-dwarf mutants of barley. p. 73-80. In Semi-dwarf cereal mutants and their use in cross-breeding. Int’l Atomic Energy Agency, Vienna, IAEA-TECDOC-268.
Ullrich, S.E. and C.B. Muir. 1984. Progress in the evaluation, use in breeding and genetic analysis of semi-dwarf mutants of barley. p. 31-38. In Semi-dwarf cereal mutants and their use in cross-breeding II. Int’l Atomic Energy Agency, Vienna, IAEA-TECDOC-307.
Ullrich, S.E., R.A. Nilan, T.M. Seaman, A.L. Hodgson, J.M. Sever and
C.N. Coon. 1984. Evaluation and breeding for proanthocyanidin-free barley.
Barley Newsletter 27:65.
