A new procedure to prepare slides of metaphase chromosomes of roses

To our knowledge, there has been no published technique to produce consistently high-quality slides of somatic chromosomes of roses (Rosa sp.), Therefore, various pretreatments, fixatives, digestions, stains, and maceration and squashing methods were tested to identify a procedure to produce clear, well-spread chromosomes from shoot tips, The best results were obtained after pretreatment in a mixture of 0.1% colchicine and 0.001 M 8-hydroxyquinoline for 4 h, and fixation in 2 acetone : 1 acetic acid (v/v) with 2% (w/v) polyvinylpyrrolidone. The darkest-stained chromosomes were obtained with carbolfuchsin staining of air-dried cell suspensions that had been spread in 3 ethanol : 1 acetic acid (v/v).