1975 Volume 40 Issue 2 Pages 333-345
Cytogenetic relationships between two diploid species belonging to genus Papaver section Orthorhoeades (Papaver syriacum f. adpresso-setulosum Boiss; P. rhoeas Lin.) is assessed using several parameters e.g. morphology, cytology, extent of crossing and cytogenetic display of hybrids and amphiploids. Even F2 populations have also been analysed cytogenetically.
Both the species had normal meiotic course and 7 bivalents were formed at metaphase I; there was preponderance of rod bivalents in the P. syriacum. The hybrids between the two species had reduced chromosome pairing and less chiasma frequency compared to the parents. Univalents and heteromorphic rod bivalents were deciphered at metaphase I of the FI's. Our studies also indicated structural differences between chromosomes of two species. The presence of multivalents in the diploid hybrids suggested heterogenity for segmental arrangements within the two species and pachynema studies supported such inferences. The genetic differentiation of two species paralleled phenotypic differentiation. The F2 populations also exhibited meiotic disturbances and reduced fertility but increase in the variability of the chiasmata frequency. There were some plants with translocations also. The variability in size and number of fragments at anaphase I and anaphase II suggested their origin through chromosome breakage and reunion rather than inversion heterozygosity. The amphiploid had mean pairing as 1.54IV+.78III+8.25II+3.0I. Multivalents were low in frequency and rod bivalents were in higher percentage. Persistance of bridge-fragment configurations at anaphase I, II of the tetraploid amphiploid derivative (i.e. amphiploid) supported their origin through breakage-reunion process. Detailed taxonomic relationships of two species within themselves and with other species in the section Orthorhoeades is further discussed.
