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Phytophthora blight of vegetables caused by Phytophthora capsici 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 P. capsici. The objective of the study was to characterize the diversity of phenotypic interactions for P. capsici isolates recovered from production fields in Michoacán, Mexico, to facilitate the development of resistant cultivars. Virulence phenotypes were characterized for 12 isolates of P. capsici using 26 Capsicum annuum 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 P. capsici 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.

Frogeye leaf spot (FLS), caused by Cercospora sojina, causes significant damage to soybean in the U.S. One control strategy is the use of quinone outside inhibitor (QoI) fungicides. QoI resistant isolates were first reported in Tennessee (TN) in 2010. To investigate the disease dynamics of C. sojina, we collected 437 C. sojina isolates in 2015 from Jackson and Milan, TN and used 40 historical isolates collected from 2006–2009 from TN and ten additional states for comparison. A subset of 186 isolates, including historical isolates, were genotyped for 49 single nucleotide polymorphism (SNP) markers and the QoI resistance locus, revealing 35 unique genotypes. The genotypes clustered into three groups with two groups containing only sensitive isolates and the remaining group containing all resistant isolates and a dominant clonal lineage of 130 isolates. All 477 C. sojina isolates were genotyped for the QoI locus revealing 344 resistant and 133 sensitive isolates. All isolates collected prior to 2015 were QoI sensitive. Both mating type alleles (MAT1-1-1 and MAT1-2) were found in Jackson and Milan, TN and recovered from single lesions suggesting sexual recombination may play a role in the epidemiology of field populations. Analysis of C. sojina isolates using SNP markers proved useful to investigate population diversity and to elaborate on diversity as it relates to QoI resistance and mating type.

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Se evaluó el efecto de dos consorcios de hongos micorrícicos arbusculares (HMA) aislados de plantas de huizache (Acacia sp.) (HMA1) y de una asociación entre Larrea tridentata y Opuntia sp. (HMA2), nativas del desierto Chihuahuense, en los componentes del rendimiento y fitoquímicos en plantas de chile Jalapeño var. M crecidas bajo estrés salino en condiciones de invernadero. El diseño experimental constó de dos factores: HMA (HMA-, HMA1 y HMA2), y salinidad (testigo, 4 y 8 dS m-1) de una solución de NaCl y CaCl2, con nueve repeticiones por tratamiento. El número de esporas fue contabilizado y las plantas se inocularon con 40,000 esporas. La solución salina se aplicó 30 d después de la inoculación durante ocho semanas. El fósforo se aplicó con una solución de 44 mg L-1 de KH2PO4 a las plantas sin inocular y de 22 mg L-1 a las plantas inoculadas. La micorrización al final del experimento osciló entre 22 y 32 % en las plantas inoculadas. La salinidad afectó significativamente el desarrollo y el verdor de las plantas. Aunque el factor HMA tuvo un efecto negativo en el número de frutos, no se afectó el rendimiento en el peso fresco de los frutos. La salinidad tuvo un efecto negativo en el peso fresco de los frutos. Los HMA incrementaron significativamente el contenido de fósforo y ácido ascórbico, sin verse afectados el desarrollo y fisiología de la planta a pesar de la reducción en la cantidad de fósforo exógeno aplicado. La concentración de fósforo en los frutos fue mayor en las plantas inoculadas con HMA2. A mayor salinidad, los frutos tuvieron menor concentración de ácido ascórbico pero mayor concentración de fenoles totales en los frutos. El contenido de capsaicinoides no fue afectado por ninguno de los factores estudiados.