Genotypic response and heritability of Fusarium oxysporum resistance in tomato

[摘要] English: This study reviewed principal aspects relating to Fusarium wilt race 2 resistancein tomatoes, caused by the fungus Fusarium oxysporum f. sp. Iycopersici. Theclassification and life cycle of Fusarium wilt, the symptomatology, diseaseassessment and host-pathogen interaction was reviewed. Different methods ofdisease management were investigated, with emphasis on genetic control.Twelve inbred tomato cultivars grown in South Africa were screened forresistance to Fusarium oxysporum f. sp. Iycopersici race 2. Percentage resistantplants, and disease progress were monitored over intervals of 30 and 60 daysrespectively. Significant differences were found between cultivars for percentageresistant plants for both intervals as well as for disease progress. Five cultivars,Floradade, Rodade, Heinz 1370, Traffic Jam and Sixpack were associated withresistance after 60 days screening, while Rossol, Oxheart, Red Kaki and Romawere found to be highly susceptible after 60 days. The cultivar x day interactionwas significant for the percentage resistant plants.Fusarium wilt resistance was then studied in six of the inbred tomato cultivarsviz., Rossol, Red Kaki, Moneymaker, Rodade, Flora Dade and Heinz 1370 andtheir F1-hybrids. Percentage resistant seedlings for each cultivar and their F1-hybrids were determined after 30 and 60 days assessment. Disease progresswas also calculated. Variance analysis indicated significant genotype x dayinteraction for Fusarium wilt. Significant differences were found between entriesafter 30 and 60-days assessments as well as for disease progress. The bestFusarium wilt resistance was found in the cultivars Moneymaker, Rodade andFlora Dade. Moneymaker also had the best disease progress. Disease progressin five of the crosses Flo x Man, Flo x Ros, Rad x Ros and Man x Ros wereless than 10%. Disease progress in the F1-hybrids were significantly lower thanin the inbred lines, which emphasis the efficiency of tomato hybrids to reduce thelevels of Fusarium wilt in tomato.Another objective of this study was to determine the combining ability andheritability of Fusarium wilt resistance in tomato. Six inbred tomato cultivarsRossol, Red Kaki, Moneymaker, Rodade, Flora Dade and Heinz 1370 werecrossed in a diallelic manner to produce 15 F1-hybrids. Assessment for Fusariumwilt resistance was done after 30 and 60 days and for disease progress.Significant differences were found for GCA- and SCA- effects. The GCA: SCAratio's for 30 and 60 days assessments indicating both additive and non-additivegene actions. Disease progress was mainly controlled by dominant effects. Thenarrow sense heritabilities for Fusarium wilt resistance were respectively 12%and 8% after 30 and 60 days assessments. Significant levels of heterosis wereobserved in crosses for Fusarium wilt resistance. The cultivar Heinz 1370 hadthe largest GCA-effect while the cross Rod x Ross possessed the largest SCA-effect.PCR technology with specific DNA primers and tomato leave cDNA was used toinvestigate the presence of different single genes in six local tomato cultivars.These cultivars included Flora Dade, Rodade, Moneymaker, Heinz 1370, Rossoland Red Kaki. The presence of the single genes 12C1, 12C2, 12, 12C3 and 12C5were tested for as they were suspected of being responsible for Fusarium wiltrace 2 resistance. The 12C1and 12C2genes were identified in all cultivars exceptfor Rossol that did not possess the 12C1 gene. No 12C3 or 12C5 genes wereidentified in any cultivars. The 12 gene was only identified in Flora Dade andRodade. In three of the cultivars significant relationships could be found betweenthe 12 resistance alleles and their breeding values.

[发布机构] University of the Free State