II. 18. New brachytic mutant of spring barley variety Aramir.
I. Szarejko and M. Maluszynski (1) Department of Genetics, Silesian University, Katowice, Jagiellonska 28, Poland.
(1) M. Maluszynski. Present address: Joint FAO/IAEA Division, 1400-Vienna. P.O. Box 100, Austria.
New dwarf mutant 648 AK was obtained after mutagenic treatment by N-nitroso-N-methylurea of two-rowed, covered caryopsis, spring barley variety Aramir which is very widely cultivated in Poland. The mutant is about 40-45 cm high and its internodes, leaves and awns are shorter, nevertheless the ears are relatively long. In comparison to the parent variety, the culms are about 40% shorter while the ears are only 15%. Other characteristics of the mutant are: erect habit, dark green colour of leaves and hard waxy coating on leaves and stems. It was found that this phenotype of the mutant is controlled by a single recessive gene (Table 1).
Table 1. F2 segregation analysis of 648 AK x "parent variety" Aramir cross.
Localization of the dwarfism gene of the 648 AK mutant was carried out by crossing with the below set of translocation testers: T1-3b, T1-7f, T2-7b, T3-7c, T3-7d, T4-7b, T4-5e, T2-5a, T6-7ae, T6-7i. The linkage was only observed with the translocation tester T1-7f, which indicates the localization of the dwarfism gene 648 AK on the chromosome 1 (Table 2). The phenotype of this mutant is very similar to the marker brachytic stock, which we received from Svalof. For this reason, both forms were crossed for allelism test. All plants had the phenotype of Swedish brachytic stock in F1 progeny, which means that the dwarfism gene 648 AK is allelic to br gene.
Table 2. F2 and F3* segregation analysis of 648 AK x T1-7f cross.
The brachytic type mutants of barley have already been described several times. Holm and Aastveit (1966) and Haus (1973) received brachytic stocks, after irradiation of varieties Domen and Moravian respectively, which were allelic to the mutant found by Stadler (Powers, 1936). The mutation in br locus was also described by Tsuchiya (1974) in short-awned form ari-i38 from variety Bonus.
Mutant 648 AK was about 10 cm shorter in field as well as in greenhouse conditions in comparison with thebr marker stock from Svalof (Table 3). This result can be explained that the expression of br gene could be dependent on the genetic background or that its alleles affect, not of this same degree, the height of the plant.
References:
Haus, T.E. 1973. BGN 3:19.
Holm, E., K. Aastveit. 1966. Adv. Frontiers Plant Sci., 17:81-94.
Powers, LeRoy. 1936. Genetics 21:398-420.
Tsuchiya, T. 1974. BGN 4:80-81.
