|Dukes, Sr., Philip|
Submitted to: Plant Genetic Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2005
Publication Date: 12/12/2005
Citation: Fery, R.L., Dukes, Sr., P.D. 2005. Potential for utilization of pepper germplasm with variable resistance to Sclerotium rolfsii Sacc. to develop southern blight resistant pepper (Capsicum annuerm L) cultivars. Plant Genetic Resources. 3(3):326-330. Interpretive Summary: Southern blight, a stem disease caused by the fungal pathogen Sclerotium rolfsii, is recognized as a major disease of pepper in most of the tropical and subtropical regions of the world. The soil fumigant methyl bromide has been the primary pesticide used in the U.S. for over 30 years to control this disease in bell peppers. The provisions of the Montreal Protocol will lead to a complete phase out of methyl bromide by 1 January 2005, and this means there is a need to develop alternative strategies for controlling southern blight in bell peppers. USDA scientists reported that the 1948 vintage bell pepper Golden California Wonder was resistant to southern blight. Because the efficient and effective use of any disease resistance in a plant breeding program is dependent upon an understanding of the inheritance of the trait, this study was initiated to determine the inheritance of southern blight resistance in Golden California Wonder. The results of this study demonstrated that resistance to southern blight in Golden California Wonder is controlled by a single recessive gene. This means that the development of southern blight resistant varieties of bell peppers is a feasible objective for a pepper breeding program. The availability of resistant varieties would eliminate the need to use pesticides to control southern blight in bell pepper plantings.
Technical Abstract: The bell type pepper cultivar Golden California Wonder, a source of resistance to southern blight incited by Sclerotium rolfsii, was crossed with the susceptible cultivar Sweet Banana. The F1, F2, and backcross progenies of this cross and the parental lines were evaluated in an inoculated field study for reaction to S. rolfsii. A categorical rating system was used to rate plants for severity of wilting and severity of stem lesion development. The plants within all three non segregating populations (the resistant parent, the susceptible parent, and the F1) displayed a range of reactions to S. rolfsii. Accordingly, a weighting procedure was used to correct the F2 and backcross populations for mis classifications in the parental and F1 populations. Examination of the comparative frequency distributions of the parental and progeny populations and examination of the weighted segregation data indicates that the southern blight resistance in 'Golden California Wonder' is conditioned by a single recessive gene. We propose that this gene be designated southern blight resistance and symbolized sbr. The level of resistance conditioned by sbr gene appears high enough to recommend it for use in pepper breeding programs.