Cytogenetics of a Trispecific Hybrid (N. benthamiana×N. glutinosa)×N. tabacum and its Allopolyploids in Genus Nicotiana

Abstract

The study pertains to the cytogenetics of a newly synthesised trispecific hybrid N. benthamiana (n=19)×N. glutinosa (n=12)×N. tabacum and its allopolyploids. The F₁ (n=55) plants were phenotypically identical and by colchicine treatment 2 partial and 2 complete allopolyploids were obtained. The study show that it is not possible to maintain the stability in these allopolyploids, when chromosome number is increased beyond certain limit. However they are useful to understand certain fundamental aspects of evolution. Recently the trispecific hybrids have gained additional importance as they offer an excellent tool to combine two non-crossable species through a ‘bridge’, thus makeing it possible to transfer disease or pest resistance traits from wild species to the species of commerce, N. tabacum.