Chromosome Behaviour and Pachytene Morphology of Coix gigantea

Abstract

Detailed cytological studies have been made on Coix gigantea which often occurs as a weed in paddy fields of South India. This cyto-type shows the aneuploid chromosome numbers of n=6 and 2n=12. All the six bivalents are homologous showing complete pairing during meiosis. The pachytene studies show significant similarities between the IInd and Vth pair of chromosomes. The Ist and VIth pair show terminal knobs. The cytological evidence indicates the relationship of this cyto-type (2n=12) with the other cyto-types of C. gigantea, but its origin is obscure. This plant could survive in the paddy fields as it exhibits mimicry together with a short life-cycle. A wide collection fom different regions of South India and detailed cytological analysis might help us to understand its phylogenetic relationships.