Intraspecific Euploidy (2<i>x</i>, 4<i>x</i>) in <i>Primula denticulata</i> Sm. from North West Himalayas in India

Abstract

The existence of intraspecific euploidy (2n=22, 44) in Primula denticulata have been reported in the present study from the higher hills of NorthWest Himalayas in India. Both the cytotypes showed perfect bivalent formation, regular meiotic course and high pollen fertility. One of the 4x accessions showed a phenomenon of cytomixis and cell fusion resulting to syncytes in meiotic cells. Consequent to chromatin transfer and cell fusion the meiocytes showed various meiotic irregularities, and sterile and heterogeneous pollen grains. The 2x and 4x plants could be distinguished on the basis of some morphometric parameters. The 4x plants are more vigorous growing much taller and possessed gigantism in leaf and floral characters besides increase in size of stomata, trichomes and pollen grains. Analysis of meiotic chromosome pairing in the 4x plants indicate towards the alloploid nature. The presence of cytomixis and syncytes/polyploid meiocytes might have played a role in the production of unreduced large-sized pollen grains facilitating the origin of new polyploids through the formation of such diplogametes. Polyploidy in particularly euploidy, seems to have played a role in the evolution of genus Primula as 38 species depicted polyploid cytotypes including 18 species which showed euploid cytotype.