1Plant Science and Technology College，Beijing University of Agriculture，Beijing 102206，China；2National Engineering Research Center for Vegetables，Beijing Academy of Agriculture and Forestry Sciences，Key Laboratory of Biology and Genetic Improvement of Horticultural Crops（North China），Ministry of Agriculture，Beijing Vegetable Germplasm Improvement Lab，Beijing 100097，China
Abstract：Based on the molecular markers tightly linked to Fon-1 for Fusarium oxysporum f. sp. niveum race 1 resistance in the diploid watermelon developed in our laboratory，the fine mapping of Fon-1 was finished in this study. A backcross population of susceptible recurrent parent NF3 and resistant donor parent JH was constructed. The newly developed SNP marker was used for Fon-1 resistance marker- assisted selection and seedling inoculation identification in different generations. The results showed that the ratio of resistant plants post-inoculated was 12.64%–15.34% lower than the ratio of resistantgenotype detected by molecular marker. The reason is that because of gene dosage effect，different heterozygosity genotype have different resistance in tetraploid watermelon as follow：AAAa > AAaa > Aaaa. At present the molecular marker could not detect the gene dosage effect or identify the susceptible genotype Aaaa. In the 673 plants BC1F2 population，we detected 29 homozygous resistant genotype（AAAA），accounting for 4.31% of the total number of plants. All of the 29 homozygous plants showed Fon-1 resistance by screening with inoculation of Fon race 1.
2015, Vol. 42 
