Virulence Phenotypes on Chili Pepper for Phytophthora capsici Isolates from Michoacán, Mexico

Abstract

<jats:p><jats:italic>Phytophthora</jats:italic> blight of vegetables caused by <jats:italic>Phytophthora capsici</jats:italic> causes significant economic losses in production of Solanaceae and Cucurbitaceae crops in Mexico. The development of universal resistant chili pepper cultivars is challenging due to the diverse virulence phenotypes produced by <jats:italic>P</jats:italic>. <jats:italic>capsici</jats:italic>. The objective of the study was to characterize the diversity of phenotypic interactions for <jats:italic>P</jats:italic>. <jats:italic>capsici</jats:italic> isolates recovered from production fields in Michoacán, Mexico, to facilitate the development of resistant cultivars. Virulence phenotypes were characterized for 12 isolates of <jats:italic>P</jats:italic>. <jats:italic>capsici</jats:italic> using 26 <jats:italic>Capsicum annuum</jats:italic> New Mexico Recombinant Inbred Lines (NMRILs) in greenhouse conditions. Criollo de Morelos CM-334 and California Wonder were used as resistant and susceptible controls, respectively. Seedlings at the four to eight true leaf stage were inoculated with 10,000 zoospores per seedling and disease severity was evaluated at 20 days post-inoculation. Two of the <jats:italic>P. capsici</jats:italic> isolates did not infect any pepper host even though the isolate was less than a year old. The 10 virulent isolates were designated in 10 virulence phenotypes. The information generated by this study is of utmost importance for efforts of producing resistant cultivars specific for Michoacán producers.</jats:p>

Morphological characterization of Phytophthora capsici isolates from Jalisco and Michoacán, Mexico

“…P. capsici was identified as the causal agent in a total of 14 isolates (seven correspond to a pathogenicity test conducted in a previous study (Reyes-Tena et al, 2019a) and 27 are associated to wilt disease in cucurbitaceae and solanaceae crops in the Jalisco and Michoacán municipalities where samples were collected. The morphological identification was in agreement with the molecular identification in a sample of isolates (Reyes-Tena et al, 2019a;Reyes-Tena et al, 2019b).…”

“…Pathogenicity test. The pathogenicity of seven isolates (CPV259, CPV260, CPV267, CPV271, CPV272, CPV277 and CPV279) was determined in a previous study (Reyes-Tena et al, 2019a). In this study, a group of seven isolates (CPV282, CPV290, CPV291, CPV293, CPV296, CPV297 and CPV301) was additionally selected to conduct pathogenicity tests.…”

“…These 14 isolates corresponded to different hosts, municipalities both of Michoacán and Jalisco, and the two mating types. The production of inoculum and chili pepper seedlings was carried out following the protocol described by Reyes-Tena et al, (2019a). Planting and production of seedlings of the California Wonder susceptible variety was carried out in 100 cm 3 six-cell trays filled with Mix 3 (Sunshine ® ) as substrate.…”

“…Prueba de Patogenicidad. La patogenicidad de siete aislados (CPV259, CPV260, CPV267, CPV271, CPV272, CPV277 y CPV279) se determinó en un estudio previo (Reyes-Tena et al, 2019a). En el presente estudio se seleccionó adicionalmente un grupo de siete aislados para realizar pruebas de patogenicidad, estos fueron CPV282, CPV290, CPV291, CPV293, CPV296, CPV297 y CPV301.…”

“…Estos 14 aislados correspondieron a diferentes hospedantes, municipios tanto de Michoacán como de Jalisco y los dos tipos de compatibilidad. Para la producción de inóculo y desarrollo de plántulas de chile se siguió el protocolo descrito por Reyes- Tena et al, (2019a). La siembra y producción de plántulas de la variedad susceptible California Wonder se realizó en bandejas de seis celdas de 100 cm 3 con Mezcla 3 (Sunshine®) como sustrato.…”