Karyotype And Ploidy Research On Several Species In Cerasus (rosaceae)

The cherry genus or Cerasus (Rosaceae-Prunoideae) was a worldwide famous ornamentalflowering plant and has a rich wild resources in China. Karyotype analysis and flow cytometrystudy of this genus was conducted in this thesis. The main results were as follows:1. Five species of Cerasus were examined in this study. For the observation of somaticchromosomes, root tips were pretreated in paracide saturated solution at4oC for4-6hours beforefixing in Carnoy’s solution at4oC for24h. The fixed material was macerated in1N HCl(hydrochloric acid) at60oC for6.5min, and then stained in carbol fuchsin and squashed beforeobserving under an Olympus microscope. Combining chromosome data from Tropicos and thisstudy, basic chromosome number of Cerasus was proved to be x=8. Chromosome number wasproved to be three types:2n=16,2n=24and2n=32. Taxa of wild species were confirmed diploid,and polyploidy phenomenon was remarkable in cultivars. Chromosome number of C.jamasakura, C. maximowiczii, C. sargentii, C. tomentosa, C. humilis, C. yedoensis, C. serrulata,C. avium was counted as2n=16. Edible cherry C. pseudocerasus was counted as2n=16,2n=24,and2n=32. C. vulgaris was counted as2n=2x=16and2n=4x=32. C. mahaleb was counted as2n=3x=24. Ornamental cherries such as C. subhirtella, C. subhirtella ‘Autumunalis’ was countedas2n=3x=24. There are four chromosome types in this genus: positive metacentric chromosomes(M), metacentric chromosomes (m), nearly metacentric chromosomes (sm) and nearly terminalchromosomes (st). Satellites were common. Karyotype types were identified as2A,2B and1B.2. Cluster analysis of several species of Cerasus was made by using DPS software with amaximum distance method to explore the relationship among species based on the karyotypeparameters. The result showed that C. subhirtella, C. subhirtella ‘Autumunalis’ and C. yedoensisstayed together, supporting the morphological sect. Sargentella. Diploid C. vulgaris and C. aviumstayed together, supporting the sect. Cerasus. Genetic distance between C. jamasakura and C.serrulata was longer than between C. jamasakura and C. campanulata. Polyploidy in cultivatedspecies was significantly higher than in wild species, showing a long genetic distance to theirdiploid ancestors. However, karyotype analysis and cluster analysis were difficult to explain theorigin of cultivated species. Unlike moporphological evidence, subg. Cerasus and subg.Microcerasus had not been apparently separated by cluster analysis.3. Five nuclear isolation buffer, Otto I, Chopping, LB01, GPB and WPB, were tested asmutually controlled trials, and the Chopping buffer was proved the optimal group for flowcytometry. Two fluorescent dyes, PI and DAPI, were tested in flow cytometry experiments, andboth revealed pleased results. Finally, a sophisticated methodology system for mass samplesploidy detection on Cerasus by using flow cytometry was developed. Compared with the traditional squash methods, flow cytometry techniques showed great advantages and broadprospects in ploidy identification and genetic breeding in Cerasus.