Chromosome sectioning optimization and chromosome counting of three cultivars of Pogostemon cablin

The roots of Pogostemon cablin (Blanco) Benth were used to study the influence of different sampling time袁 pretreatment liquid袁pretreatment time, enzyme concentration, enzymolysis time and hypotonic time on the chromosome sectioning. The chromosome number of three cultivars (P. cablin. cv. shipaiensis袁P. cablin. cv. gaoyaoensis袁P. cablin. cv. hainanensis) was counted by the wall degradation hypotonic method. The results showed that the materials were drew in 10:30-11:00 a.m., then pretreated with ice-water mixed liquor for 24 h, and with 4% mixed enzyme liquid 渊contains 4% cellulase and 4%pectinase袁g/V冤for 30 min. After hypotonic treatment for 15 min, 50 metaphase cells of each cultivar were observed. Chromosome number of more than 70% cell was 2n = 64. There was no difference on chromosome number in three cultivars of P. cablin.