| Sugarcane smut caused by Ustilago scitaminea Svd. was a main disease in the world. It has spread out all over the world and causes serious loss in stalk yield and sucrose content in susceptible varieties. More serious loss was observed sugarcane planted in droughty land. It was accepted universally that planting resistance varieties was the most effective measure. Smut resistance was one of main breeding goal in USA, Brazil, Cuba and China et aI.. Efficiency of breeding for disease resistance was affected directly by the method used in identification of disease resistance. By the time, resistance identification was also conducted by artificial inoculation and cultivation in the field. Beside, the indicator for identification was single. it was necessary for establishing a perfect system for identification of smut resistance and .developing of molecular marker for mark-assisted selection (MAS). Making use of MAS, first step, molecular marker linked to smut resistance gene must be selected, but it was still not reported in the world. In our research, some material derived from a single cross of CO 1001 XYa7I-374 were taken as test material. Inoculation experiment was conducted in two crops of plant cane and one crop of ratoon. The method of resistance identification in field was perfected by taking standard varieties as control and by cluster analysis on multiple indicators. On the basis of it, sugarcane smut resistant or susceptible pools were constructed. Bulked segregant analysis (BSA) was employed to identify a RAPD marker linked stability to sugarcane resistance gene. This work has provided a solid basis for MAS for smut resistance and for cloning of smut resistance gene. The results of correlation coefficient showed that correlation between disease epidemic parameter of SDD, IP;nax, Y~n ax, and AUDPC was significant at 0.05 or 0.01 level, results of correlation analysis were similar in different crops. It suggested that single indicator of IP,nax, Ytnax orAUDPC being used as the indicator of smut resistance identification was reasonable in some degree. Analysis on stability of resistance showed that resistant repeatability in various resistant types of material was significant different from plant cane to ratoon and from plant cane to plant cane. Rate of repeatability was varied from 10.0 percentage to 100.0 percentage. Repeatability in material of HR or HS was highest, then was R or 5, repeatability in material of MR or MS was lowest. It indicated that relative unquestionable results of resistance identification in material of HR or HS could be gained by a few number of inoculation. Results of resistance identification showed that the value of each disease epidemic parameter in same material was different in various crops. Besides, results of resistant arrangement according to the value of single JPrnax, Yrnax or AUDPC was various in most of test material in same crop. It suggested that resistance identification by multiple ?VIII ? indicators and by installment of standard varieties in test was necessary. By cluster analysis on LI? SDD, IPmax, Ymax and A UDPC and reference to standard varieties, a assessment of tested material was made. R and S bulked pools that can be used in linked marker for target character were constructed. By optimization of PCR parameters, a steady RAPD system of sugarcane was established. In total volume of 25uL, contained 2.5tiL lOX PCR buffer, lSng template DNA, 2.0rnmol.L~?Mg2~, l2Oumol.IJ抎NTPs and I unit Taq polymerase. S...
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