Chromosome analysis in the dioecious cucurbit Coccinia grandis (L.) Voigt

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 CMApositive signals in different chromosomes. Detailed meiotic analysis has been carried out from diakinesis and metaphase I to establish genomic stability.