Cytosystematics of three Onobrychis species (Fabaceae) in Iran

Abstract

In this study, we describe the morphological characters and meiotic chromosome number and behavior of different wild populations belonging to Onobrychis viciifolia Scop., O. transcaucasica Grossh. and O. altissima Grossh. belonging to Onobrychis sect. Onobrychis in Iran. All Iranian populations of O. viciifolia and O. altissima studied here were tetraploid and showed 2n = 4x = 28 chromosome number, but O. transcaucasica populations were diploid. The basic chromosome number (x = 7) is consistent with the proposed base number for O. viciifolia and O. altissima from IPCN. For O. altissima, two ploidy levels (2n = 2x = 14 and 2n = 4x = 28) have been previously reported from Caucasus. The fact that no diploid populations of O. altissima were found in Iran, would suggest a relatively recent origin of the species, most probably in Caucasus. Although O. transcaucasica is diploid, its remarkable similarities in morphology to O. viciifolia and O. altissima can be suggested its relatively recent origin for these taxa. Almost all taxa studied here displayed regular bivalent pairing and chromosome segregation at meiosis. However, meiotic abnormalities observed included varied degree of sticky and fragmented chromosomes, laggards and bridges in anaphase to telophase, desynapsis in anaphase I and metaphase II, asynchronous nuclei and cytomixis. © 2010 Taylor and Francis Group, LLC.