Types of chromosomal aberrations induced by seed aging in Crepis capillaris

The types of chromosomal aberrations during the aging of Crepis capillaris (Hawksbeard; fam. Asteraceae) seeds were investigated. Seeds were stored at 22 degrees C for 2, 4, 6, and 8 years. Chromosomal aberrations were analyzed in metaphase chromosomes at the first and second mitotic cycles. A colchicine block was used for the differentiation of individual mitotic cycles. The frequency of chromosomal aberrations induced during seed aging gradually increased with the increase in the time of aging, reaching its maximal value after 8 years of aging. Both chromatid and chromosome types of aberrations were observed in first mitosis. At all times of aging, the frequency of chromosome-type aberrations considerably surpassed the frequency of the chromatid type. At the different times of aging, the frequency of chromosome-type aberrations was 3-4.5 times higher than that of chromatid-type aberrations. In the second mitosis, the frequency of both aberration types was low. The frequency and type of derived chromosomal aberrations observed in second mitosis corresponded to those observed in first mitosis. These results are discussed in relation to the factors inducing chromosome lesions during seed aging and the mechanism of formation of chromosomal aberrations.