meiotic study was performed in 11 brassica napus cultivars considering chiasma frequency anddistribution, chromosome pairing, as well as the occurrence of b-chromosomes and their effects on chiasmafrequency. such cytogenetic pairing, along with agronomic characteristics, may be used in planninghybridization among the b. napus cultivars. all the cultivars studied possessed n=19 chromosome number...

a cytogenetic study was performed on 11 tetraploid cotton cultivars (gossypium hirsutum l.)including the oltan cultivar and its crossing progenies. the chromosome pairing and chiasma frequency, aswell as meiotic abnormalities were compared among the genotypes studied. heterozygote translocations withalternate orientation were observed between some of the chromosomes of the a genome and those of...

the genus onobrychis belongs to family fabaceae and has about 130 species throughout the world. onobrychis sect. hymenobrychis with nearly 14 species in iran is one of the important sections of the genus. the chromosome number and meiotic behaviour were studied in two populations of onobrychis chorassanica belonging to this section native to iran. this report is the first cytogenetic analysis o...

in the present paper, the cytogenetic study including meiotic chromosome number and behavior along with pollen viability were performed in 4 populations of trigonella spruneriana boiss. this is the first cytogenetic report of the taxon. all populations are diploid and possess 2n = 2x = 16 chromosome number, which is consistent with the proposed basic number of x = 8. in addition, some meiotic i...

B chromosomes are extra chromosomes to the standard complement that occur in many organisms. They can originate in a number of ways including derivation from autosomes and sex chromosomes in intra- and interspecies crosses. Their subsequent molecular evolution resembles that of univalent sex chromosomes, which involves gene silencing, heterochromatinization and the accumulation of repetitive DN...

chromosome counting was performed in nine populations of achillea tenuifolia lam and eight populations of a. bieberestinii afan (asteraceae) collected from hamedan and kermanshah provinces in the west of iran. chromosome numbers in both species varied from 2n=2x=18 to 2n=4x=36. some populations of both species showed (2n=4x=36) chromosome number that is the first report as polyploidy levels. an...