Karyological Variation between Two Taxa of Plantago major L., ssp. major and ssp. intermedia (Gilib.) Lange

R. El-Bakatoushi, A. J. Richards
2005 CYTOLOGIA  
The two taxa Plantago major ssp. major and ssp. intermedia from different geographical regions were investigated karyologically. The separation of the two taxa depends mainly on seed number and size. The average karyotypic configuration for each population was used to contrast ideograms between populations from ssp. major and ssp. intermedia. The study revealed that the two taxa have distinct cytotypes which are somewhat correlated with seed number as an indication of taxonomic identity. The
more » ... iation between two taxa is expressed by two main cytological groups based on the total form percentage (TF %) which measures the symmetry of the chromosomes over the whole karyotype. The study also revealed that the evolution of the P. major group may be in part due to chromosomal rearrangement. The study concluded that most major karyotypes are more symmetrical than those of intermedia, which may be an indication that intermedia is the derived type. The first consistent chromosome counts in Plantago were reported by McCullagh (1934) . Other studies were made in connection with taxonomic studies in order to explain the relationships in particular groups of related species (Böcher et al. 1955 , Rahn 1957 , Cartier 1971 , Zemskova 1977 . Studies also covered the cytology of Plantago species from different phytogeographic regions (Gregor 1939 , Runemark 1969 , Briggs 1973 . Badr and El-Kholy (1987) studied Plantago chromosomes in the Egyptian flora. Of the 10 studied species, five were found to have a basic number of xϭ6: P. arabica, P. lagopus, P. lanceolata, P. major and P. notata. The study revealed that P. major was characterised by short chromosomes and a symmetric karyotype compared with other species. In general, the karyotype in Plantago consists of medium-sized chromosomes, mostly with meta-and submetacentric constrictions, with no marked size difference between individuals in the total length of the chromosome complement. One or two pairs of chromosomes possessed secondary constrictions. The chromosomes of Plantago could be classified as metacentric, submetacentric, or subterminal. Pramanik and Sen Raychaudhuri (1997) studied the karyograms of some species of Plantago obtained from different parts of the world and revealed that karyograms had standard features. Despite homogeneity in total features, each species differed from the other in minor karyotypic details indicating the role of structural changes of chromosomes in evolution. The basic chromosome number xϭ6 is the most common among the species Plantago and may be considered the ancestral number in the genus (Badr et al. 1987) . Material and methods Seeds were sown from two taxa Plantago major L. ssp. major ('major') and ssp. intermedia (Gilib.) Lange ('intermedia') all of which were of known identity except for one location (Table 1) .
doi:10.1508/cytologia.70.365 fatcat:k4f5ocgs4ffqldyoguxrmmjmli