Submitted to: HortScience
Publication Type: Germplasm Release
Publication Acceptance Date: November 12, 1996
Publication Date: N/A
Interpretive Summary: The southern root-knot nematode is a serious pest of many crops. Although plant breeders have been quite successful in developing resistant varieties, they are often handicapped in their efforts because of the expense incurred in production of the large amount of nematode inoculum (nematode eggs) needed to evaluate the resistance characteristics of their breeding lines. The USDA has released a new cayenne pepper, designated PA-136, that is an exeptional host for the production of southern root-knot nematode inoculum. Root-knot nematode-infected PA-136 plants produce tremendous numbers of nematode eggs; the root system of a single PA-136 plant can produce enough eggs for a plant breeder to evaluate 2,000 plants for resistance to root-knot nematodes. Unlike other commonly used host plants, PA-136 plants tolerate heavy nematode infestations without succumbing to secondary root diseases. With adequate care, root-knot nematode-infected PA-136 plants will remain in good condition for extended periods thereby allowing a long time interval for extraction of large numbers of eggs. The utilization of PA-136 to produce inoculum should increase the efficiency of plant breeding efforts to develop root-knot nematode resistant cultivars.
Technical Abstract: The USDA has released a cayenne-type pepper (Capsicum annuum) germplasm line for use as a host for the production of southern root-knot nematode (Meloidogyne incognita) inoculum. The new germplasm line, designated PA-136, was derived from a single plant that was selected in 1981 from a 'Carolina Hot' population that was heterogeneous for many traits, including gplant habit, fruit color, and resistance to root-knot nematodes. Four to six weeks after inoculation with M. incognita eggs, numerous small galls bearing large egg masses develop on PA-136 roots. Abundant egg production continues for several months. The eggs are easily extracted using 0.1% NaOCl. The root system of a single, greenhouse-grown plant yields an average of 4.4 million eggs. The root systems of M. incognita-infected PA-136 plants do not appear to be as susceptible to root diseases caused by secondary plant pathogens as do the root systems of other host plants commonly used to produce M. incognita inoculum. With adequate care, M. incognita-infected PA-136 plants will remain in good condition for extended periods thereby allowing a long time interval for extraction of the large numbers of eggs needed for use as inoculum in plant germplasm evaluation studies.