Spontaneous mutation frequencies in barley

Full text: Estimation of the spontaneous mutation frequency requires screening of very large populations and has therefore rarely been carried out in higher plants. A study on inter-allelic recombination in the ml-o locus allowed to collect some data on spontaneous chlorophyll mutants. 1866 barley plants were progeny tested in the greenhouse. 25 plants segregated for newly arisen, spontaneous chlorophyll mutant genes. Among a total of 470129 seedlings screened there were 79 mutants (1.7±0.6x10-4). If these data are pooled with others from similar materials the resulting estimate is 1.6x10-4 in about 1,43 million seedlings. The estimate of the chlorophyll mutation rate per generation is close to 6.3x10-4 per diploid genome. Assuming that the number of loci that can give rise to chlorophyll mutants is in the order of 500, the spontaneous mutation rate would be in the order of 6x10-7 per locus and haploid genome per generation. (author)