Analysis Of Karyotype And Establishment Of FISH System Of Ulva Prolifera

The large-scale outbreak of the green tide has become a serious ecological disaster in the Yellow Sea,and UlvaProlifera is one of the dominant species of the green tide.U.prolifera organisms have special breeding methods and complex stages of life history.At present,research on its growth and development conditions and life history has been common.However,since Ulva has a very thick polysaccharide cell wall and a small chromosome,the chromosome morphology under the light microscope is not easy to be recognized.The extranuclear genetic material(chloroplast DNA,mitochondrial DNA)in the organelle is large,and it is easy to be colored by the basic dye to bring a serious background interference.Therefore,the research on Ulva chromosome production technology is very limited.This study is aimed at the above-mentioned U.prolifera chromosome production difficult,so can not analyze the karyotype and other issues,U.prolifera as a material,using enzymatic de-walling method to prepare chromosome slides,analysis of U.prolifera chromosome karyotype and cytogenetics studies were performed by labeling 5S rDNA fragments on chromosomes using a fluorescence in situ hybridization system.The study found that the number of chromosomes of U.prolifera haplotypes is n=10,the number of chromosomes of diploid sporozoites is 2n=20,and the number of chromosome bases is determined to be 10.And for the first time,the karyotype formula of U.prolifera chromosome was obtained:n=x=10=9 m+1 sm.It is clear that the 10 chromosomes of gametophytic cells are composed of 9 central centromere chromosomes(m)and 1 near middle the centromere chromosome(sm)is composed.The optimized enzymatic hydrolysis method for preparing protoplasts of Brassica oleracea meets the requirements of flow cytometry.The results of flow cytometry showed that the sporozoites were 2±0.31 times of the nuclear DNA content of gametophytes.It indicates that U.prolifera is accompanied by sexual and asexual generations in the process of green tide outbreak in the Yellow Sea.The gametophyte and sporophyte continuously grow and multiply.The fluorescence in situ hybridization detection system localizes the 55 rDNA sequence to the metaphase chromosome of U.prolifera somatic cells,and clarifies the distribution of 5S rDNA on chromosome 1-5.It provides a technical basis for the physical localization of Ulva species genes and also contributes to molecular cytogenetic studies of Ulva species.