Karyomorphological Study of Melilotus Officinalis in Iranian Populations

Background and aim: yellow sweet clover (melilotus officinalis), a member of family fabaceae, is of medicinal and agricultural important. cytogenetic analyses is diagnostic tool useful in chromosome identification and selection of superior populations. the aim of the research was investigation the karyomorphological characteristics between 4 iranian populations of genus melilotus officinalis.methods: the seeds of four iranian populations of melilotus officinalis were placed in an incubator at 20 - 25oc for germination and then, the root tips meristems were studied. root tips, 1-2 cm in length, were excised and pretreated in 2 mm solution of 8- hydroxiquinoline at 4 oc for 3-4 h, washed in distilled water and fixed in lewitski fixative at 4 o c for 36 h. roots were rinsed in distilled water and then treated with 1 n noh at 60 o c for 10 min. then, the roots were washed in distilled water for 30 min and followed by staining in aceto- hematoxylin-iron at 30-34 o c for 15-20 h. the stained roots were squashed in a drop of acetic acid 45% and finally the squashes were studied under microscope.results: the haploid chromosome number reported for this genus is x=8. the results of the present study showed there was no evidence of shifts in chromosome number of experimental populations compare to previous cases. according to the observations, the chromosome types were near metacentric and sub metacentric that was expressed in other studies, too. it was also recognized one pairs of satellite in metaphase chromosomes in all 4 populations which has been not reported before in the genus. the satellites placed in different regions of chromosome so that, they located in short arms of homologues chromosomes in one population but in the other three populations they placed on long and short arms of homologues chromosomes.conclusion: finding the satellites in the experimental populations shows structural difference between iranian sweet clover germplasm compare to other previously studied germplasm. also, it was seen heteromorphic chromosomes in some studied populations especially in satellite chromosome that represents chromosomal changes during evolution in the populations of melilotus officinalis.