Study On Cytology Of 6 Wild Taxa And 10 Cultivars Of Rubus L.

This thesis focuses on cytology research of 6 wild taxa and 10 cultivars of Rubus, including the study of chromosome karyotypes and meiotic activities of pollen mother cells by applying squash method.The connection between phylogenesis and genome structural,variation were discussed.The results concluded as following.No aneuploids wre found in all the 16 materials studied.In the 6 wild taxa, chromosome numbers of 14 were found in all the 5 plants of Sect.Idaeobatus Focke,and the karuotype formulae of 2n=2x=12m(2SAT)+2sm(2SAT),2n=2x=14=12m(2SAT)+2sm, 2n=2x=14=14m were found respectively in the taxa R.ellipticus var.obcordatus,in the taxa R.amabilis,in the 3 taxa R.coreanus,R.corchorifolius and R.niveus.There were 28 chromosomes found in R.lambertianus var.glaber of Sect.Malachobatus Fock.In the 10 cultivars,chromosome numbers of 14 were found in all the 4 Raspberry cultivars,and the karuotype formulae of 2n=2x=14=14m and 2n=2x=14=14m(2SAT) were found respectively in the cultivar 'Dinkum',in the 3 cultivars 'Chilcotin','Nova' and 'Bristol'. While three various chromosome numbers of 28,42 and 49 were found in the 6 Blackberry cultivars,their karyotypes formulae were as follows:'Arapaho' and 'Shawnee', 2n=4x=28=28m;'Ollalie',2n=6x=42=38m(6SAT)+4sm;'Black Butte','Boysen' and 'Kotata',2n=7x=49=49m.The karyotypes of all the taxa,except that of R.ellipticus var. obcordatus and 'Ollalie',which were composed of metacentric chromosomes and submetacentric chromosomes and had a karyotype asymmetry type 2A,were composed of metacentric chromosomes with a type 1A asymmetry.The indexations of flower buds and anther during meiosis of 16 brambles had been investigated.Using the small buds of R.ellipticus var.obcordatus,'Arapaho','Ollalie' and 'Boysen' as main materials,the key factors such as the sampling time and environmental temperature when sampling materials,fixating agents(Carnoy'sⅠ, improved-Carnoy'sⅡand Carnoy'sⅡ),temperatures and times,dissociating agents(HCl) at different concentrations,temperature and times,which influenced the preparation of chromosome,had been studied.Based on the contrasts of numbers of metaphaseⅠin PMCs,the difficulty of techniques,the degree of treatment complications and the fact that chromosomes were distinct and countable from their background under microscope,the suitable method for chromosome preparation of Rubus was as follows:sampling materials when the buds were 2.0～6.7mm in diameter while the PMCs in the stage of meiosis, fixating with improved-Carnoy'sⅡ,dissociating with 0.5 mol /L HCl at 20～25℃for 4～10min,and staining with carbol fuchsin solution.The chromosomes obtained by the preparation method described above could be used for the study of meiosis.In this study,meiotic processes of pollen mother cells(PMCs) in 16 taxa of Rubus were observed and the pollen vigor was assessed.Cytokinesis was simultaneous type.The chromosome pairing configuration in meiosis MI per PMC of each one layed,The everage meiotic associations at metaphaseⅠin PMCs of 9 diploids of R.ellipticus var.obcordatus,R.coreanus,corchorifolius/ R.amabilis,R.niveus,Chilcotin','Dinkrum','Nova' and 'Bristol'are 0.08Ⅰ+6.96Ⅱ,7Ⅱ,7Ⅱ,7Ⅱ,7Ⅱ,0.29Ⅰ+6.85Ⅱ,0.15Ⅰ+6.88Ⅱ,0.28Ⅰ+6.86Ⅱand 0.67Ⅰ+6.33Ⅱ+0.12Ⅲ+0.10Ⅳ;tetraploids of R.lambertianus var.glaber 'Arapaho' ansd 'Shawnee' are 0.67Ⅰ+6.33Ⅱ+0.12Ⅲ+0.10Ⅳ,0.20Ⅰ+12.80Ⅱ+0.27Ⅲ+1.90Ⅳand 0.67Ⅰ+6.33Ⅱ+0.12Ⅲ+0.10Ⅳ;1 hexaploids of 'Ollalie' 0.67Ⅰ+ 6.33Ⅱ+0.12Ⅲ+0.10Ⅳ;and 3 heptapoids of 'Black Butte','Boysen' and 'Kotata' are 5.28Ⅰ+15.81Ⅱ+2.57Ⅲ+1.00Ⅳ, 8.17Ⅰ+18.00Ⅱ+1.16Ⅲ+0.35Ⅳ和5.22Ⅰ+15.24Ⅱ+1.87Ⅲ+1.67Ⅳ.Abnormalities of meiosis in Rubus comprised partly bivalent disjunction,chromosome bridge,lagged chromosome and fragment,micronuclei and so on,there was obvious chromosome fractionation in the heptaploids of blackberry.Meiotic partly nonsynchronous division was ubiquitous in the course of meiosis in polyploids blackberry,some of bivalents disjuncted at diakinese in diploids of raspberry.Structural variations such as chromosome inversion and translocation on some chromosome might play important roles in the process of phylogenesis of Rubus L.R.lambertianus var.glaber and'Arapaho' were supposed to be allopolyploid,while 'Shawnee' and 'Ollalie' to be segmental allopolyploid or autopolyploid,'Black Butte','Boysen' and'Kotata' to be segmental allopolyploid.