Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2003
Publication Date: January 6, 2004
Citation: Haynes, K.G., Goth, R.W., Lambert, D.H., Christ, B.J. Late blight resistance in a tetraploid potato population with horizontal resistance [abstract]. American Journal of Potato Research. 2004. 81:65.
A population of tetraploid potatoes with horizontal resistance to late blight was developed at the International Potato Center in Lima, Peru. True seed from this population was obtained from the NRSP-6 Project at Sturgeon Bay, WI for the purpose of evaluating its potential to contribute to the breeding effort for late blight resistance in the United States. In 1996, 552 single hills were planted on Chapman Farm, Presque Isle, ME; only 448 tuberized. In 1997 these clones were planted on Chapman Farm for increase; 129 were saved, 53 failed to tuberize, and 266 were discarded because they were sprouting at harvest. In 1998 and 1999, 69 of these clones were evaluated for their reaction to the US-8 strain of late blight in replicated plots on Aroostook Farm. Percent infected foliage was estimated three times towards the end of the season and used to compute area under the disease progress curve (AUDPC). There were significant difference among the clones for the square root of AUDPC (sAUDPC): 55 of them were significantly more resistant than "Atlantic". There was also a significant clone x year interaction for sAIDPC. Broad-sense heritability for horizontal resistance to late blight was estimated as 0.78 with a 95% confidence interval of 0.64 to 0.86. Using detached leaf assays these clones were inoculated with US-8 strains of P. infestans and the diameter of the lesion was measured 7,8,9,10, and 11 days after inoculation. The correlations between field resistance and the detached leaf assay were very low (0.18<r<0.24). Based on field tests, this population is an excellent source of genetic resistance to late blight. (Poster, breeding)