Cytogenetic studies in the genus Matthiola.

Cytogenetic studies in the genus Matthiola by Magda I.M. Soliman The present study on the genus Matthiola has been carried out from the cytological view-point. The following taxa were used: M. farinose, M. fruticulosa ssp. fruticulosa. M. fruticulosa ssp. perennis, M. fruticulosa ssp. valesiaca, M. incana, M. longipetala ssp. bicornis, M. lunata, M. maderensis, M. maroccana, M. parviflora, M. odoratissima, M. ovatifolia, M. sinuate, and M. tricuspidata. All the species were of wild origin except M. longipetala ssp. bicornis which is a cultivated strain. All the species examined are diploid. More than one basic number is present in the genus; x=6 and x=7. The somatic chromosome number reports for M. farinosa collected from U.S.S.R., M. lunata from Algeria, M. maderensis from Madeira (Porto Santo and San Gorge) and M. maroccana from Morocco were new reports. Geographically Matthiola is a Mediterranean genus. From the results of this work, it appears that the 14 chromosome species occur mainly in the western and the 12 chromosome species mainly in the eastern part of the generic range. It is evident from the karyotype studies that none of the Matthiola species have an identical chromosome set. Nuclear DNA contents have been estimated for Matthiola species for the first time in this study. In Matthiola, the variation in the amount of DNA is not related to chromosome numbers but there is a positive relationship between 2C DNA content and complement length. The mean 2C DNA values of the different accessions of Matthiola species were statistically significantly different at the 0.001% level. The mean 2C nuclear DNA content for annuals and perennials did not show any difference in Matthiola, however inbreeding species had greater amounts of DNA than outbreeding. Meiosis is regular in most of the species studied, but in M. sinuata and M. longipetala ssp. bicornis it is slightly irregular. Mean chiasma frequency per cell was highest in M. incana and lowest in M. lunata. Species of the genus Matthiola have been artificially hybridized in this study for the first time. Some crosses were successful in producing F1 flowering plants, and meiotic analysis of these hybrids was undertaken. The evolution of chromosome numbers in the genus is discussed, in relation to the results incorporated in this thesis.