Inheritance of Phytophthora Root Rot and Foliar Blight Resistance in Pepper

Abstract

<jats:p>The inheritance of resistance to <jats:italic>Phytophthora capsici</jats:italic> Leonian root rot and foliar blight was compared in two different <jats:italic>Capsicum annuum</jats:italic> L. var. <jats:italic>annuum</jats:italic> pod types. The seedling was screened for phytophthora root rot, while a genetically identical stem cutting was screened for phytophthora foliar blight to determine if the same gene(s) confer resistance to both disease syndromes. The susceptible parents were `Keystone Resistant Giant #3' (`Keystone'), a bell pepper type, and `Early Jalapeño', while `Criollo de Morelos-334' was the resistant parent. Resistance was observed in both F<jats:sub>1</jats:sub> populations screened for phytophthora root and foliar infection indicating dominance for resistance. Reciprocal effects were not detected. To determine if the same gene(s) conferred root rot and foliar resistance, root rot screening results were matched to the corresponding foliar blight stem cutting reaction. The segregation of resistance in the F<jats:sub>2</jats:sub> generations was dependent on the susceptible parent. In the F<jats:sub>2</jats:sub> generation derived from `Early Jalapeño', root rot resistance and foliar blight resistance segregated in a 9:3:3:1 (root resistant/foliar resistant: root resistant/foliar susceptible: root susceptible/foliar resistant: root susceptible/foliar susceptible) ratio. One independent, dominant gene was necessary for root rot resistance, and a different independent, dominant gene was needed for foliar blight resistance. In the F<jats:sub>2</jats:sub> generation derived from `Keystone', root rot and foliar blight resistance segregated in a 7:2:2:5 (root resistant/foliar resistant: root resistant/foliar susceptible: root susceptible/foliar resistant: root susceptible/foliar susceptible) ratio. This segregation ratio is expected when one dominant gene is required for root resistance, and a different dominant gene is required for foliar resistance. In addition to these two genes, at least one dominant allele of a third gene must be present for expression of root rot and foliar blight resistance.</jats:p>

Pepper morphological traits related with resistance to Phytophthora capsici

“…The progenitor SCM-334 always showed 100 % survival and, in addition, all the members of F 1 were resistant (Table 1). These results agree with those of Walker and Bosland (1999) as regards the dominance of resistance in the F 1 generation.…”

“…The most convincing results suggest that resistance to P. capsici in SCM-334 pepper plants is polygenic and that the three genes that confirm resistance provoke a susceptible-resistant gradient in the segregating generations (Palloix 1986, Gil Ortega et al 1992. However, other researchers have suggested that resistance in SCM-334 might be based on a two gene model (Guerrero and Laborde 1980), while, more recently, Walker and Bosland (1999) observed that the segregation of resistance in F 1 was dominant, but the number of genes required in the F 2 plants is dependent on the susceptible parent.…”

Evaluation of Eggplant Rootstocks and Pepper Varieties for Potential Resistance to Isolates of Phytophthora capsici from Michigan and New York

“…Tbe pepper line CM334 bas been extensively tested against isolates worldwide and bas demonstrated resistance to isolates of P. capsici in addition to otber pathogens, but its usefulness as a rootstock is limited (20,27,30,31). Tbe eggplant lines EG195 and EG203 were intermediately to fully resistant to all 14 of tbe P. capsici isolates tested in tbis study.…”

Identification and Expression Analysis of Candidate Genes Associated with Defense Responses to Phytophthora capsici in Pepper Line “PI 201234”

“…Root rot is one of the most serious disease symptoms, which can result in plant wilting and death when plants are infected with P. capsici [1]. The spread of P. capsici is accelerated by high temperatures and humidity and is managed through cultural practices, fungicide applications and the use of resistant cultivars [2].…”