PJB-2020-207
KARYO-MORPHOLOGICAL ANALYSIS OF DRIMIA ALTISSIMA AND DRIMIA VIRIDULA; TWO OF THE THREE SPECIES IN URGINEA ALTISSIMA COMPLEX OF THE FAMILY HYACINTHACEAE
SIKIRU BABATUNDE OMOKANYE
Abstract
The Urginea (syn: Drimia) is a heterogeneous, poorly understood genus of flowering plants which requires taxonomic revision. Chromosome behaviour of Urginea gigantea (Jacq.) Oyewole. and Urginea viridula Baker; two species in U. altissima (L.) Baker. complex were studied to determine the origin, mechanism of transmission of extra chromosomes pair and its roles in pollen viability. Conventional cytogenetic and karyotype analysis were used for the study. Chromosome numbers were 2n = 22 and 2n = 20 for U. gigantea and U. viridula respectively. Extra chromosome pair in U. gigantea resulted into 2n = 22. Average chromosome length was 55.45 mm for U. viridula and 55.50 mm for U. gigantea. Bridge formation, laggards, chromosome exclusion and formation of 9 (3.26%), 10 (90.93%) and 11(5.81%) chromosome bodies were observed in U. gigantea, however, U. viridula consistently formed10 bivalents. Pollen viability was 90.63% in U. gigantea and 94.95% in U. viridula. Karyotypic evidence suggests that an extra chromosome pair in U. gigantea evolved from chromosome fragmentation of the second-largest chromosome, not a B-chromosome because it participated in cell division. High pollen viability correlated with percentage occurrence of ten bivalents, indicating that U. viridula, is closer to the progenitors of a common genetic system within U. altissima complex and the existed karyo-morphological differences supports the separation of the two taxa as distinct species. Keywords: Chiasma formation, chromosome bodies, karyo-morphology, pollen viability, Urginea gigantea, Urginea viridula
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