Comparative male meiotic studies in some Indian representative species ofCucumisL. (Cucurbitaceae)

Abstract

Male meiotic studies in eight Indian Cucumis species, including two newly included species, have been carried out. Gametic chromosome numbers of n = 7 and 12 were recorded in these taxa. Data collected on chromosome associations, chiasma frequency at diplotene/diakinesis/metaphase I revealed the predominant occurrence of bivalents in the majority of the pollen mother cells (PMCs) of taxa having n = 7, suggesting a high degree of homology among the pairing chromosomes. Conversely, species with n = 12 had chromosome associations resulting in a mixed of bivalents and univalents. One of the reasons for such heterogeneity exclusively found in these species may be attributed to chromosome structural alteration at DNA level (duplication/deletion/point mutation) rather than numerical alteration. Multivalents were not encountered in any of the PMCs, indicating the diploid nature of the taxa. A single nucleolus showing affinity towards varying numbers of bivalents (1-4) was the hallmark feature of the PMCs analyzed at diplotene.

Genetic System of  Cucumis sativus var. hardwickii (Royle) Alef. –   (wild cucumber) in Jammu, J&K, India

“…Cytologically, wild variety of cultivated cucumber is stable in nature with diploid chromosome number of 2n = 14 at Metaphase -I and equal segregation of chromosomes (7:7) at Anaphase I. This stable chromosome number was also reported by Singh and Roy (1974) and Rajkumari et al, (2013). But the existence of tetraploid cells in this wild variety of cucumber is not on record.…”