II. 19 Mutation frequencies obtained after sodium azide treatment in different barley varieties.
B. Jende-Strid, Department of Physiology, Carlsberg Laboratory, C1. Carlsberg Vej 10, DK-2500 Copenhagen Valby, Denmark.
Sodium azide has been discovered as a very efficient mutagen in barley by Nilan and coworkers (cf, Sander and Nilan, 1974). Treatment of the 2-row spring barley varieties: Alf, Bonus, Nordal, Gula Abed, Ark Royal and Triump gave high but differing frequencies of chlorophyll-deficient mutations.
The seeds were presoaked in distilled water at +5°C without oxygen bubbling or at room temperature with O2 bubbling for various lengths of time and then treated in a solution of NaN3 at pH 3.0 for 2 hrs. (Table 1). The NaN3 solution was bubbled with O2 during the treatment. Afterwards the seeds were rinsed in water and planted wet in the field. The seeds germinated almost normally except for seeds treated with concentrations of azide higher than 10-3 M. Seeds treated with 10-2M azide did not germinate at all. Up to 10% of the M1 plants had striated leaves. The frequencies varied among the varities being highest in Nordal. About 200 M1 spikes from 200 different plants in each treatment were planted under standard greenhouse conditions and the number of chlorophyll-deficient mutants counted. As evident from Table 1 the mutation frequencies differed among the varieties and years. Variations in the pre-treatments did not change the mutation frequencies in a systematic way.
Table 1. Induction of chlorophylldeficient mutants by sodium azide.
From the M2 generation of Nordal and Alf (treated in 1976) a large number of viable mutants were obtained. In an M2 population of Nordal consisting of ca. 150.000 plants, 500 short strawed, 415 early maturing and 140 mutants with improved mildew resistance were selected. The materials are also being screened for hordein mutants, high lysine mutants and mutants with a low content of beta-glucans.
Reference:
Sander, C. and R.A. Nilan. 1974. Increasing the mutagenic efficiency
of sodium azide in barley. Barley Genetics Newsletter 4, 63-65.
