|
DNA content per nucleus in Aegilops species Yoshihiko FURUTA Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan Genus Aegilops includes about 20 species that have been thoroughly investigated from the cytogenetical viewpoint. In order to enhance further understanding of the phylogenetic relationships among these species, their nuclear DNA content was measured microspectrophotometrically, using the pollen tetrad nuclei stained by Feulgen's method (NISHIKAWA and FURUTA 1969, Jap. J. Genet. 44). The results obtained are shown in Table 1, together with chromosome number and genome constitution. Analysis of variance revealed that the difference between nine diploid species (11 strains) was significant. DNA content per nucleus of Ae. bicornis was apparently the highest among all diploid species. No significant difference was found among Ae. longissima, Ae. mutica, Ae. uniaristata and Ae. comosa, between Ae. umbellulata and Ae. squarrosa var. meyeri, and among Ae. squarrosa var. meyeri, var. strangulata and Ae. caudata, respectively, while the difference was significant among all other species combinations. Moreover, Ae. squarrosa var. typica showed the lowest amount of nuclear DNA among 11 diploid strains. In the tetraploids, no significant difference was found among two subspecies of Ae. triuncialis (amphidiploid between Ae. caudata and Ae. umbellulata) and the sum of its two analysers. On the other hand, a statistically significant difference was noted among five species, Ae. variabilis, Ae. ovata, Ae. columnaris, Ae. biuncialis and Ae. triaristata 4x which belong to Polyeides section. DNA content of Ae. cylindrica was approximate to the total of those of Ae. caudata, donor of C genome and Ae. squarrosa var. meyeri or var. strangulata (but not var. typica), a D genome donor. This result is contradictory to that of JOHNSON (1967, Nature 216) obtained by protein electrophoresis which suggested Ae. squarrosa var. typica as the possible D genome donor to Ae. cylindrica. No difference was observed between Ae. crassa 4x and Ae. ventricosa, both of which had DNA content almost comparable to the sum of Ae. comosa or Ae. uniaristata and Ae. squarrosa. As to the hexaploid species, Ae. triaristata 6x showed DNA content that is equivalent to the sum of Ae. triaristata 4x and Ae. comosa or Ae. uniaristata. Ae. crassa 6x and Ae. vavilovii also showed an additive relationship between their ancestries, that is, these hexaploids had DNA content nearly equal to the sum of Ae. crassa 4x and Ae. squarrosa and Ae. crassa 4x and Ae. longissima, respectively. In another hexaploid species, Ae. juvenalis, the observed value was higher than the expected one based on its putative ancestry. In general, actual DNA content of polyploid species was comparable to that expected from their genome constitution. (Details of the results and discussion will be presented elsewhere.) (Received January 28, 1970) |