BGS319     Reaction to Puccinia graminis f. sp. tritici        rpg4

	   (Wheat Stem Rust)

Previous nomenclature and gene symbolization:
None.

Inheritance:
Monofactorial recessive (3, 4).
Located in chromosome 7L, in sub-terminal position about 4.9 cM distal from MWG 740 (1).

Description:
The rpg4 gene confers low infection types to pathotypes QCC and MCC of the wheat stem rust pathogen (Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. &. Henn.) at the seedling stage under low incubation temperatures 18-22^deg.C (3, 4). This gene is ineffective (exhibits compatible infection types) against pathotypes QCC and MCC at incubation temperatures greater than 25 °C. At the adult plant stage, rpg4 confers a moderate to high level of resistance to pathotype QCC (2).

Origin of mutant:
Natural occurrence in Q21861, but its pedigree can not be traced.

Mutational events:
rpg4.d in Q21861.

Mutant used for description and seed stock:
rpg4.d in Q21861 (PI 584766).

References:

1. Borovkova, I. G., B. J. Steffenson, Y. Jin, J. B. Rasmussen, A. Kilian, A. Kleinhofs, B. G. Rossnagel, and K. N. Kao. 1995. Identification of molecular markers linked to the stem rust resistance gene rpg4 in barley. Phytopathology 85 (in press).

2. Jin, Y., B. J. Steffenson, and T. G. Fetch, Jr. 1994. Sources of resistance to pathotype QCC of Puccinia graminis f. sp. tritici in barley. Crop Sci. 34:285-288.

3. Jin, Y., B. J. Steffenson, and J. D. Miller. 1994. Inheritance of resistance to pathotypes QCC and MCC of Puccinia graminis f. sp. tritici in barley line Q21861 and temperature effects on the expression of resistance. Phytopathology 84:452-455.

4. Steffenson, B. J., Y. Jin, B. G. Rossnagel, and K. Kao. 1995. Genetics of multiple disease resistance in a doubled haploid population of barley. Plant Breed. 113 (in press).

Prepared:
Yue Jin and Brian J. Steffenson. 1995.

BGS 542

Previous nomenclature and gene symbol:
None

Inheritance:
Monofactorial dominant, chromosomal location unknown

Description:
Mutant plants are approximately 50% of the height of the normal plants and are insensitive to exogenous gibberellic acid (GA3). The mutant plants tiller profusely, have shortened (7cm vs 13cm), dark green leaves and smaller seed (28mg vs 46mg) than normal plants, and are much later in flowering and maturing. This mutant is very different from dwf1 in barley (BGN 12:106; BGN 12:69-72) and the known semidwarf mutants.

Origin:
The mutant described occurred as a chimeric somaclonal mutation via anther culture in H930-36 (H930-36 = doubled haploid from Klages/Mata via Bulbosum). It was a single tiller on an otherwise normal height plant. The seed grown from that tiller segregated for three dwarf : one normal height plant, indicating that the original tiller was heterozygous for the dominant mutation.

Mutational events:
Dwf2 occurred as a spontaneous mutation in an anther culture-derived plant of H930-36.

Mutant used for description and seed stock:
Dwf2 in H930-36

References:
Falk, DE and KJ Kasha. 1982. Vegetative dwarf, new gene description. BGN 12:106.

Falk, DE and KJ Kasha. 1982. A vegetative dwarf mutant in barley. BGN 12:69-72.

Prepared by:
D.E. Falk