A STUDY OF KARYOTYPES IN THE CROCUS SATIVUS L. AGGREGATE AND ORIGIN OF CULTIVATED SAFFRON

A karyotype study of close to C. sativus L. wild-growing diploid relatives is rather topical for finding out about their mutual relations among themselves and with C. sativus L. We investigated karyotypes of some species of the specified series with application of the advanced method developed by one of us (Agayev) which combines the positive moments of fixation of root tips with chrome-formol by Lewitsky, staining chromosomes in aceto-iron-hematoxylin and maceration of stained roots by means of the enzyme cytase. The table on parameters of chromosomes, and also karyograms are worked out for the following species and forms: C. sativus L., C. sativus L. 'Kashmirianus', C. cartwrightianus Herb., C. oreocreticus B.L. Burtt, C. hadriaticus Herb. (forms 859, 861 and 862) and partly C. pallasii Goldb. subsp. haussknechtii (Boiss and Reut. ex Maw) Mathew. We have established that at a usual species C. sativus L. and at its variant 'Kashmirianus' karyotypes are surprisingly identical. It is especially necessary to emphasize that the heteromorphic chromosomes 5.1 and 5.2, 3 are surprisingly similar between them and it undoubtedly testifies that these plants certainly are descendants of one predecessor. At the same time and their differences are so essential, that they can be considered taxonomically as independent cultivars: at 'Kashmirianus' the homologs of the second-largest chromosomes, all three, have satellites of almost identical average sizes, whereas at usual sativus those are as a rule of different sizes. Total length of 2n=3x=24 chromosomes is significantly more at 'Kashmirianus' comparing with sativus. At 'Kashmirianus' chromosomes 4.1, 2 and 4.3 not so much, but significantly differ on arm ratio, while such difference is absent at sativus. Now for the species C. cartwrightianus the homologs of chromosomes 5 and 8 differ from each other significantly on arm ratio, chromosomes 1, 2 and 4 are subacrocentrics, and 3, 5.2, 6 and 8 metacentrics. For the species C. hadriaticus three forms differing in structure of karyotype are revealed. Chromosomes 3 at forms 859a and 862a are obvious heteromorphic, and at the form 861a both homologs are metacentrics. There are some differences and between forms 859a and 862a in morphology of other chromosomes. In structure of the karyotype the species C. cartwrightianus, and C. oreocreticus mostly suit to C. sativus, but there are also differences. C. hadriaticus suits less. Nevertheless, these conclusions are preliminary and require further research.