II. 1. Ethyl methane sulfonate induced short awned mutations.
A. S. Khalatkar, R. J. Thengane and Y. R. Bhargava, Department of Botany, Nagpur University Campus, Nagpur 440010, India.
Although the induced mutation programme in Himalayan hull-less barley with physical and chemical mutagens is in progress for about ten years in our laboratory, we were recently able to induce short awned mutations at a low frequency with ethyl methane sulfonate. At present, these mutants are in the fifth generation and have been observed to breed true. The mutants obtained could be classified into three catagories, viz. triple, double and single short awns on the basis of different degrees of reduction in the awn lengths. The awn lengths of these mutants were 1.5, 2.7 and 4.2 cm, respectively, compared to 12.0 cm in control (Fig. 1). The morphological characteristics of mutants and control plants are presented in Table 1. The plant population belonging to the above mentioned three categories was similar, except for the awn lengths.
Figure 1. Control and short awned spikes.
Initially, the growth in mutant plants was slower than control; however, at maturity they were taller than control plants. Although the internodal number in mutants was lower than control, the internodes were longer. The leaves were slightly shorter and narrower. However, the straw of the mutant plants was stiffer. The meiosis in mutants exhibited 8.4% PMCs with chromosomal abnormalities. Consequently, 8.3% pollen grains were sterile. Compared to control, heading was 11 days later than control. As a result, the maturation time was also more than that of normal plants.
Table 1. Morphological characteristics of mutant and control plants.
The mutant spikes were 9% shorter and the overall seed-set was approximately 20% lesser compared to control plants. Seeds were smaller and as a result, the weight of 1000 seeds was also lower in mutant plants. Further, the aleurone layer had lesser or no pigmentation.
Although the differences in the reproductive characters and seed-set were small, when the seeds were analysed by Dye Binding Capacity (DBC) technique for proteins, they were found to differ from control considerably. All the three categories of short awned mutations had significantly higher protein levels. The triple short awned mutation was around 20% richer in protein content. The relationship between the lower total seed weight and the higher protein content was obvious. However, in some cases this relationship did not hold good.
Acknowledgment:
The authors are thankful to Dr. H. C. Bansal for the data on protein
analysis.
