Studies on root tip chromosome squashes in Lilium and karyotype analysis of four Lilium species

摘要

The technique of preparing chromosome squashes of the root tip is the key to analyzing the karyotype of Lilium. Different pretreatment chemicals (0.1% colchicine, 0.002 M 8-hydroxyquinoline), pretreatment times (12, 24, 36h), dissociating time (5, 10,20 min) and staining solutions (acetocarmine and carbol fuchsin) were compared. Optimum chromosome squash results were obtained when the root tips were pretreated in 0.1% colchicine at 4°C for 24 h, hydrolyzed with 1 M HC1 for 10 min at 60°C, and thenstained with carbol fuchsin solution. Subsequently, we carried out karyotype analysis of four Lilium species, Lilium formosanum, Lilium longiflorum, Lilium regale and Oriental Lilium 'Siberia' on the basis of this optimized method. The results indicatedthat the karyotypes of four Lilium species all were 3B. The karyotype formulae were 2n=2x=24=4m(2SAT (satellite))+2sm(2SAT)+6st+12t for L. formosanum, 2n=2x=24=2m+2sm+6st(2SAT)+14t for L. longiflorum, 2n=2x=24=2m (2SAT)+2sm+6st+14t for L. regale, and 2n=2x=24=4sm(2SAT)+10st(4SAT)+10t for Oriental Lilium 'Siberia'. Asymmetrical karyotype coefficients were 79.59, 80.17,80.12, and 81.28, respectively, which indicated that the degree of evolution was: Oriental Lilium 'Siberia' > L. longiflorum >L. regale > L. formosanum. In conclusion, with this method, good chromosome squash results could be obtained. Karyotypes of four Lilium species were achieved and their evolutionary relationships were discussed, which might provide a cytological basis for research into the evolution, breeding and genetics of lily.