Karyotype Analysis And The Microdissection Of Single Chromosome Of The Cauliflower

Cauliflower (Brassica oleracea .vsx.botrytis L) is one of the most important vegetables. It is very practically meaningful to study karyotype and to microdissect single chromosome of cauliflower for establishing its DNA library and genetic map as well as cloning its key genes. In this paper, the cauliflower variety, "Fuzhou 60 day", was used as experimental material for following studies.1.The experimental conditions of karyotype analysis and miscrodisscetion were optimized. The results were shown as follows:(1)Very good chromosome samples were obtained by macerating 60癈 IN HC1 for 10 minutes, and similar effect could also be obtained by macerating IN HC1 for 12-16 minutes at room temperature.(2)When the root length was about 0.5cm was the best time to pretreat.(3)Good shape of chromosomes could be obtained and the chromosomes were easy to be identified by pretreating with 8-Hydroxyquinoline, a-Bromonaphthalene, Cycloheximide and p-Dichlorobenzene. And pretreatment with 8-Hydroxyquinoline could reach the best result, namely, chromosomes were fairly well-dispersed, the primary and secondary constrictions were distinct and the chromosomes with satellite were easy to be identified.(4)For microdissection, the chromosome sample should further be macerated with a solution containing 2% cellulase and 2% pectinase at 37癈 for 1~1.5 hour, which could refrain from the background interference of cytoplasm and cell wall.2.The analysis of karyotype of "Fuzhou 60 day" showed that: the somatic chromosome numbers were 2n=18, the chromosome with satellite was located in chromosome 7 with a arm ratio 2.01. The length of the chromosomes was between 2.05 and 3.9Q\im, the relative length was between 7.97% and 15.17%. Chromosome 1 and 7 were sub-metacentric chromosomes with arm ratio between 1.71 and 3.00, and the rest were metacenrric chromosomes with arm ratio between1.01 and 1.70. The length ratio of the longest and shortest chromosome was less 2.0, the average arm ratio was 1.62, which indicated that the chromosome type of "Fuzhou 60 day" belonged to 2A type, a symmetrical karyotype.3.The chromosome with satellite was identified and successfully isolated with glass needle by means of micromanipulation. One of the rest chromosomes was also microdissected. These provided a possible chance for microcloning of single chromosome in Brassica oleracea vsx.botrytis L.