Abstract
Karyotype analysis and meiotic behavior in a dioecious cucurbit Coccinia grandis, carrying heteromorphic sex chromosomes, has been carried out using conventional and fluorochrome dyes. Distinct differences in karyotype formula with 15m+4M+2sm+2m: sm+1m: st for male plant and 14m+6M+2sm+2m: st for female plant were observed with orcein staining. In both cases one autosome pair with two constrictions was present. Male plants are seen to possess a heteromorphic Y chromosome with two constrictions which is sufficiently larger than other small sized chromosomes. Giemsa followed by CMA/ DAPI staining through EMA method applied for the first time in this dioecious species, revealed CMA-positive signals in different chromosomes. Detailed meiotic analysis has been carried out from diakinesis and metaphase I to establish genomic stability.
