Use of image cytometry for the early screening of induced autopolyploids

The rapid and early detection of autotetraploid individuals is a fundamental requirement in genetic improvement programmes based on chromosome duplication. Counting chromosomes provides certainty of the ploidy level of an individual, however, it is very laborious. In this work, image cytometry is proposed as an easy alternative method to detect tetraploid individuals. Plantlets of the species Rhodophiala montana treated with colchicine were karyomorphologically analysed. Based on the Feulgen stain, chromosomes were counted and the integrated density value of interphase nuclei was determined. The average DNA content measured with image cytometry for the polyploid individuals was 1.88 times more than that for the diploid individuals. With this methodology, 100% effectiveness in the selection was achieved, rapidly identifying all autotetraploid individuals.