Meiotic Chromosome Numbers in 9 Iranian Species of Oryzopsis (Poaceae)

抄録

Meiotic studies were performed in 9 Oryzopsis species of O. pubiflora, O. lateralis, O. holciformis, O. barbellata, O. munroi, O. microcarpa, O. sphacelata, O. virescense and O. molinioides showing the presence of 2n=2x=24 in all nine species studied. The species studied were diploid and had 12 chromosome number, and in O. microcarpa, O. sphacelata, O. molinioides and O. virescense chromosomes are new count. B-chromosomes 0–2 were observed in all species studied, which were smaller than A-chromosomes and did not pair with them. T-test analysis between the cells with B-chromosomes and those devoid of Bs showed significant difference in chiasma frequency and distribution as well as in chromosomes pairing only in O. munroi, with significant reduction in meiotic values in the presence of B-chromosomes. The occurrence of large pollen grains (possibly unreduced pollen grains) was observed along with small (normal) pollen grains in these species. Significant difference observed in chiasma frequency and distribution among species studied may be of use in species delimitation. Moreover species relationships obtained based on cytological data partly supports taxonomic treatment of the genus.