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Updated: Feb 25, 2026
An Effective Inoculation Method for Phytophthora capsici on Black Pepper Plants
Published on: September 16, 2022
Disease Resistance to Multiple Fungal and Oomycete Pathogens Evaluated Using a Recombinant Inbred Line Population in
R P Naegele1, L L Granke1, J Fry1
1First author: Research Horticulturalist, United States Department of Agriculture-Agricultural Research Service Crop Diseases, Pests and Genetics Research Unit, Parlier, CA 93720; second author: Associate Research Scientist, Dow Agrosciences, Indianapolis, IN 46268; third author: Former Graduate Research Assistant, Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824; fourth author: Senior Research Associate, Department of Plant Sciences, University of California, Davis 95616; fifth author: Assistant Professor, North Carolina State University, Raleigh 27695-7550; sixth author: Director of Research, Seed Biotechnology Center, University of California, Davis; and seventh author: Professor, Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing 48824.
Modern pepper breeding aims to enhance disease resistance by introgressing genes from wild relatives. This study evaluated a recombinant inbred line population for resistance to multiple pathogens, finding genetic linkages but no specific sites of multiple disease resistance.
Area of Science:
- Plant breeding
- Genetics
- Pathology
Background:
- Incorporating disease resistance into commercial cultivars is crucial for modern agriculture.
- Resistance is often sourced from landraces or wild relatives, which may have undesirable traits.
- Sites of multiple disease resistance (MDR) are genomic regions with linked resistance genes for efficient breeding.
Purpose of the Study:
- To identify quantitative trait loci (QTL) associated with disease resistance in a pepper recombinant inbred line population.
- To investigate the presence of sites of multiple disease resistance (MDR) for various fungal and oomycete pathogens.
- To assess correlations in disease susceptibility among different pathogens in pepper.
Main Methods:
- An F2-derived F6 recombinant inbred line (RIL) population from a cross between 'Criollo de Morelos 334' (CMM334) and 'Early Jalapeno' was developed.
- RILs were evaluated for susceptibility to ten different oomycete and fungal pathogens, including Phytophthora capsici, Botrytis cinerea, and Alternaria spp.
- Quantitative trait loci (QTL) mapping and correlation analyses were performed to identify resistance genes and disease associations.
Main Results:
- Significant variation in disease susceptibility was observed among the RILs for each pathogen.
- Phytophthora capsici exhibited the highest virulence, while Rhizopus oryzae and one Sclerotinia isolate were least virulent.
- QTL for resistance were identified for Alternaria spp. and Sclerotinia sclerotiorum. Positive correlations in disease incidence were found between several pathogens, suggesting potential genetic linkage.
Conclusions:
- No specific sites of multiple disease resistance (MDR) were identified for the tested pathogens.
- Positive correlations among pathogen disease incidence suggest potential genetic linkages for resistance in the CMM334 and Early Jalapeno parents.
- Further research into these genetic linkages could facilitate the development of multi-pathogen resistant pepper cultivars.
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