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This article in CS

  1. Vol. 32 No. 2, p. 310-312
     
    Received: Oct 8, 1990


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doi:10.2135/cropsci1992.0011183X003200020004x

Use of Pathogen Filtrate to Differentiate Physiological Resistance of Dry Bean to White Mold Disease

  1. P. N. Miklas ,
  2. K. F. Grafton,
  3. G. A. Secor and
  4. P. E. McClean
  1. USDA-ARS, Tropical Agric. Res. Stn., P.O. Box 70, Marquez, PR 00681
    Dep. of Crop and Weed Sci.
    Dep. of Plant Pathology, North Dakota State Univ., Fargo, ND 58105

Abstract

Abstract

White mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is major concern to the dry bean (Phaseolus vulgaris L.) industry because it reduces yield. Incorporating partial physiological resistance (PPR) into bean is one strategy to combat the disease, but this requires a reliable screening technique. The objective of this work was to develop a reliable screening method to identify bean germplasm that express PPR to S. sclerotiorum. An in vitro method that assayed weight of calli formed on a medium amended with crude culture filtrate of S. sclerotiorum was evaluated. Hypocotyl explants of eight bean genotypes (six cultivars, a breeding line, and one plant introduction), taken from 7-d-old seedlings, were incubated for 15 d on a solid Murashige and Skoog-based medium, containing 5.0 μM/ kinetin and 2.5 μM picloram, and amended with 200 mL L−1 culture or control filtrate. Callus fresh weight, expressed as a percent of the control (CWPC), was analyzed over two runs. Lack of a genotype × run interaction, and a genotypeffect (P < 0.05) for CWPC indicated that this screening method gave repeatable results and was able to differentiate PPR among the eight genotypes. The field resistant ‘Sierra’ and ‘C-20’ had the greatest PPR, as indicated by high C-%VPC values, and the field susceptible ‘UI-114’ and ‘Upland,’ the least PPR. These results to fungal metabolites parallel field resistance of the genotypes, implicating PPR as an important component of the field reaction of a given genotype. The callus-weight assay may provide a way to differentiate dry bean germplasm for partial physiological resistance to S. sclerotiorum.

Contribution of the North Dakota State Agric. Exp. Stn. Paper no. 1928. Partial fulfillment of senior author's Ph. D. dissertation. Research was supported in part by the Quaker Oats Co.

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