Botanical And Molecular Characteristics Of Allohexaploid Between Tuber Mustard And Red Cabbage

In this study, allohexaploid So was synthesized by chromosome doubling of Ho, hybrid between tuber mustard (Brassica junced) and red cabbage (B. oleracea). After morphologic observation, chromosome counting, and flow cytometry analysis, So was used to cross with Brassica crops to get new varieties. At the same time, self cross was made on So to get Si, which can be a good material for agricultural industry and fundamental research. Botanic measurement, SRAP, and MSAP were used to analyze the characteristics of Si, and explore the genetic and epigenetic changes during the distant hybridization. The main results were summarized as follows:(1) Allohexaploid So and Si were synthesized and characteristic observation was applied on them to evaluate their application value. The best fit concentration of colchicine for chromosome doubling was100mg/L. After the treatment, So was identified to be true allohexaploid, proved to be fertile and got offspring Si by artificial pollination.(2) So was used to cross with other Brassica crops to get new varieties. The morphological characteristics of new varieties was similar to Brassica juncea and Brassica rapa,which showed application potential.(3) Physiological and biochemical indexes were analyzed in Si and parents. Heterosis of the alkenyl GS content, including2-hydroxy-3-butenyl GS,2-propenyl GS, and3-butenyl GS, was detected in Si. While its content of soluble sugar and protein, and protective enzyme activity (SOD, POD, CAT, and APX) showed intermediate type.(4) SRAP was used to analyze the genetic and epigenetic changes between Ho, So, Si, and the parents. Results showed that a large number of parental bands (19.5%) were lost in offspring, among which more bands of red cabbage were lost than tuber mustard. Results also suggested that hybridization had a greater impact on offspring of wide hybridization than chromosome doubling. MSAP was used to analyze the epigenetic changes between Si and the parents. Results showed that the methylation rate in Si (50.5%) was much less than the parents (tuber mustard was60.1%and red cabbage was63.2%) and it inherited more bands from tuber mustard than from red cabbage. MSAP was also used to analyze the epigenetic changes of Si and the parents during the vernalization. Results indicated that the induction of flower was only related to demethylation during the treatment, rather than methylation status before treatment, and that the status of methylation in Si was stable to some extent.