Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2008
Publication Date: 3/1/2009
Citation: Chenault, K.D., Maas, A.L., Damicone, J.P., Payton, M.E., Melouk, H.A. 2009. Discovery and characterization of a molecular marker for Sclerotinia minor (Jagger) resistance in peanut. Euphytica. 166:357-365. Interpretive Summary: Sclerotinia blight is a fungal disease of peanut that is widespread throughout the U.S. Few cultivars with acceptable tolerance have been developed due to the quantitative inheritance of this trait. This study reports the identification of the first molecular marker in peanut associated with Sclerotinia blight resistance. Simple sequence repeat primer pairs were used to examine peanut genomic DNA from 39 different genotypes and one pair produced bands consistent with either S. minor resistance or susceptibility. Cloning and sequencing of these bands revealed the region is well conserved among all genotypes tested with the exception of the length of the simple sequence repeat region, which varies with disease resistance levels. Statistical analysis of revealed that the SSR marker discovered was highly correlated with resistance to Sclerotinia blight in peanut. This is the first report of a molecular marker associated with resistance to Sclerotinia blight in peanut. This marker will enhance the efficiency of screening germplasm and breeding populations for Sclerotinia resistance and reduce the time required to develop new highly resistant cultivars.
Technical Abstract: The production of cultivated peanut, an important agronomic crop throughout the United States and the world, is consistently threatened by various diseases and pests. Sclerotinia minor Jagger (S. minor), the causal agent of Sclerotinia blight, is a major threat to peanut production in the Southwestern U.S., Virginia, and North Carolina. Although information on the variability of morphological traits associated with Sclerotinia blight resistance is plentiful, no molecular markers associated with resistance have been reported. The identification of markers would greatly assist peanut geneticists in selecting genotypes to be used in breeding programs. The main objective of this work was to use simple sequence repeat (SSR) primers previously reported for peanut to identify a molecular marker associated with resistance to S. minor. Out of sixteen primer pairs used to examine peanut genomic DNA from 39 different genotypes, one pair produced bands at approximately 145 bp and 100 bp, consistent with either S. minor resistance or susceptibility, respectively. Cloning and sequencing of these bands revealed the region is well conserved among all genotypes tested with the exception of the length of the simple sequence repeat region, which varies with disease resistance levels. This is the first report of a molecular marker associated with resistance to Sclerotinia blight in peanut. The identification of this marker and development of a PCR-based screening method will prove to be extremely useful to peanut breeders in screening germplasm collections and segregating populations as well as in pyramiding Sclerotinia minor resistance with other desirable traits into superior peanut lines.