|Gulya Jr, Thomas|
Submitted to: Sunflower International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/11/2004
Publication Date: 8/1/2004
Citation: Chen, J., Miller, J.F., Gulya Jr, T.J., Vick, B.A., Cai, X., Hu, J. 2004. Searching for DNA markers associated with Sclerotinia tolerance in cultivated sunflower. In: Proceedings International Sunflower Conference Proceedings, August 29-September 2, 2004, Fargo, ND. v. II. p. 631-636. Interpretive Summary: In the cultivated sunflower, no major gene has been identified resistant to the devastating fungal pathogen, Sclerotinia sclerotium. Instead, there are many quantitative trait loci (QTL) reported, each contributes additively to the partial tolerance to sclerotinia head rot or stalk rot. Pyramiding QTL from different sources via breeding into a single line would enhance the tolerance. However, environmental influence over the expression of these QTL made the identification of these QTL difficult. Use DNA markers associated with the QTL will assist the breeding process in recombining the QTL. This article reports the identification of a DNA marker, developed with the target region amplification polymorphism (TRAP) technique, associated with the sclerotinia susceptibility in a segregating population. This marker will be useful in marker assisted selection for sclerotinia resistant sunflower breeding program.
Technical Abstract: Using the in-house-developed target region amplification polymorphism (TRAP) technique, we are aggressively searching for DNA markers associated with Sclerotinia tolerance in sunflower. The F2 population of 190 plants used for the current study was derived from a three-way cross of HA412/SD//Romania Phomopsis Resistant B-line and segregated for Sclerotinia tolerance and plant height. The fixed primers for TRAP were designed against annotated EST (expressed sequence tag) homologous to identified plant disease resistance gene components such as kinase, leucine rich repeats (LRR), and nucleotide binding sites (NBS). The fixed primers in combination with fluorescently labeled arbitrary primers were used to amplify DNA fragments from genomic DNA. On average, each PCR reaction amplified 50 scorable fragments with length ranging from 50 to 900 base pairs. The number of polymorphic fragments varied from 1 to 12 per primer combination. Up to now, one hundred and two markers were generated in this population. Seventy-nine of these markers segregated in a ratio of 3:1, and thirteen segregated in a ratio of 1:1. This was expected because the population had three parental lines. One marker associated with Sclerotinia susceptibility was generated in this population. This marker sized 411 bp and amplified by the primer combination E10J20b and Ga5 was present in 15 of the 18 diseased plants and segregated in a ratio of 3:1 in the population.