U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
3-2017
Citation
ANNUAL REPORT OF THE BEAN IMPROVEMENT COOPERATIVE, No. 60, March 2017. Published by USDA.
Abstract
INTRODUCTION: White mold, caused by Sclerotinia sclerotiorum (Lib.), is one of the most important pathogens of common bean (Phaseolus vulgaris L.), causing complete crop failure under certain conditions. Several methods have been developed to evaluate physiological resistance to white mold in the laboratory and greenhouse, such as spraying plants at bloom with a suspension of ascospores, limited-term inoculation, and the excised stem test (Abawi & Grogan, 1975; Hunter et al., 1981; Miklas et al., 1992). The straw test developed by Petzoldt & Dickson (1996), is widely used to evaluate and screen for physiological resistance. This method was subsequently modified by Terán et al. (2006). The original and modified straw test use plants that are three to five weeks old at the time of inoculation, with another week of growth prior to scoring, which requires larger pots, more bench space, and more hand labor maintaining the plants. We modified the conventional straw test so that fewer resources and less time and effort are required. A companion paper (Arkwazee & Myers, 2017) provides details of the procedure, and the seedling straw test was able to successfully detect major QTLs associated with white mold resistance in common bean (Vasconcellos et al., 2017).
MATERIALS AND METHODS: Two experiments were conducted to compare the conventional (original) and seedling straw test with two different sets of accessions being used, the first being six common bean lines with known levels of resistance or susceptibility to white mold and second 28 accessions from 2017 National White Mold Nursery. The six common bean lines included G122 and NY6020-5 (resistant), Ex Rico (moderate resistance), and OSU 5630, OR 91G, and Beryl (susceptible) (Table 1.) and the 28 national white mold trial accessions are shown in Table 2. Four seeds from each line (thinned to 3 seedlings) were planted in a 2L pot with four replications for each accession.
Comments
U.S. government work.