ARS | Publication request: Prolonged infection periods to Sclerotinia sclerotiorum identified in wild pea germplasm to be breed into pea cultivars to promote disease avoidance

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2008
Publication Date: January 6, 2008
Citation: Porter, L., Coffman, V.A. 2008. Prolonged infection periods to Sclerotinia sclerotiorum identified in wild pea germplasm to be breed into pea cultivars to promote disease avoidance. Phytopathology. 98: S127.

Technical Abstract: White mold, caused by Sclerotinia sclerotiorum, is a foliar pathogen that can cause serious disease in irrigated and dryland peas. Management of white mold in peas with fungicides is not economical and resistant cultivars do not exist. Therefore, 504 wild pea accessions were screened for resistance to S. Sclerotiorum. Although all 504 lines were susceptible to infection, ten of the most resistant lines to lesion expansion were selected for further studies. The selected lines were compared to the susceptible pea cultivar Bolero for length of infection period and lesion expansion when plants were inoculated and maintained at 24 different combinations of temperature (15.6, 18.3, 21.1, 23.9, 29.4ºC) and incubation period (12, 24, 48, 72 hours) in a growth chamber at 90-100% RH. All pea lines screened at a 12-hour incubation period prevented lesion expansion beyond the inoculation point at all temperatures tested except 1204-3, 166084 and Bolero. Pea lines screened at a 24-hour incubation period were all highly susceptible to infection and lesion expansion at all six temperatures except for lines, 103709, 164972, and 169603 were resistant at 29.4ºC, and 169603 was resistant at 23.9 ºC. No pea line was resistant to infection at any of the temperatures when incubated for greater than 24 hours. Future efforts will concentrate on identifying quantitative trait loci associated with prolonged infection periods that can be used in marker-assisted selection for this trait. Identified lines will be crossed with semi-leafless upright pea cultivars to create new cultivars with prolonged infection periods that will maximize disease avoidance and have upright semi-leafless canopies that will limit environmental conditions favoring white mold.