Phytophthora infestans population structure: a worldwide scale

Phytophthora infestans, the causal agent of late blight disease in potato and other members of the Solanaceae family, is responsible for causing the Irish potato famine and, even today, it causes enormous economic losses all over the world. For the establishment of an adequate pest management strategy, the determination of population structure is required. To characterize P. infestans populations worldwide two allozymes, Gpi (Glucose-6-phospate isomerase) and Pep (Peptidase), the RG57 DNA RFLP fingerprinting probe, as well as resistance to the fungicide metalaxyl and the mating type, have been used as markers. P. infestans populations in Mexico have been one of the main focuses of research in the population biology of this pathogen because this country has been considered as one of the possible centers of origin of this oomycete. In this review we present the population structure of P. infestans in Mexico, Europe, Africa, Asia, North America, and South America expanding on the present situation of P. infestans in Colombia. Finally, we will discuss different lines of research that are being carried out today with respect to P. infestans in Colombia, which have shown the importance of continuing the study of this devastating plant pathogen in our country.Phytophthora infestans, el agente causal del tizón tardío de la papa y otros miembros de la familia de las Solanáceas, es el responsable de la gran hambruna irlandesa y aún hoy sigue causando grandes pérdidas económicas alrededor del planeta. Para establecer estrategias de control adecuadas contra este patógeno se requiere comprender la estructura poblacional del mismo. Mundialmente se han utilizado como marcadores las aloenzimas, Gpi (Glucosa-6-fosfato isomerasa) y Pep (Peptidasa) y la sonda de fingerprinting de RFLP (Polimorfismos de la Longitud de los Fragmentos de Restricción), RG57. De igual forma, la resistencia al fungicida metalaxyl y el tipo de apareamiento, han sido empleados para caracterizar las poblaciones de P. infestans. Las poblaciones de P. infestans en México han sido uno de los focos principales de investigación en la biología poblacional de este patógeno debido a que este país ha sido considerado como uno de los posibles centros de origen de este oomiceto. En esta revisión se presentará la estructura poblacional de P. infestans en México, Europa, África, Asia, Norte América y Sur América, profundizando en la situación actual de P. infestans en Colombia. Finalmente, se discutirá las diferentes líneas de investigación que se llevan a cabo hoy respecto a P. infestans en Colombia, las cuales han mostrado la importancia de continuar con el estudio de este devastador patógeno de plantas en nuestro país

The genus Phytophthora; phylogeny, speciation and host specificity

Pormotie-onderzoek naar de fylogenie, soortsvorming en waardplantspecificiteit in het geslacht Phytophthora

The Potato Crop

Life sciences; Agriculture; Nutrition   ; Plant breeding; Food—Biotechnology; Agricultural economic

Translational Genomics for Crop Breeding: Biotic Stress, Volume 1

Genomic Applications for Crop Breeding: Biotic Stress is the first of two volumes looking at the latest advances in genomic applications to crop breeding. This volume focuses on genomic-assisted advances for improving economically important crops against biotic stressors, such as viruses, fungi, nematodes, and bacteria. Looking at key advances in crops such as rice, barley, wheat, and potato amongst others, Genomic Applications for Crop Breeding: Biotic Stress will be an essential reference for crop scientists, geneticists, breeders, industry personnel and advanced students in the field

Volatile organic compounds associated with neonectria ditissima infection in apples (Malus pumila cv Gala)

Postharvest diseases in apples during long term storage result in loss and waste. This is mainly caused by fungal pathogens. Fungal contamination and rot can change some of the volatile organic compounds (VOC) emitted by apple fruits. In this study, disease free Gala apples were inoculated with Neonectria ditissima. The aim was to identify VOCs associated with N. ditissima infection in gala apples. The inoculated apples were placed in 5L glass flask, sealed, and incubated at 20oC for one hour after which a charcoal filtered airflow of 1 L/min was maintained for one hour through the Volatile Capture Trap (VCT) with volatile emissions captured on a porapak-Q absorbent filter. Captured volatiles were eluted using 1 mL of dichloromethane (DCM) into a standard Agilent 1.5 mL HPLC vial. Eluted volatiles were analysed using Gas Chromatography coupled with Mass Spectrometry (GC/MS). Volatiles were capture in three replicates for both inoculated and healthy control groups at 2 days, 8 days, 14 days, 21 days, 28 days, 35 days, and 42 days post-inoculation. The N. ditissima discriminatory volatile were identified/discriminated qualitatively based on the unique volatile compounds detected and quantitatively based on variation in peak area of certain combinations of volatile compounds. Some of the discriminatory volatiles such as dodecyl hexanoate, 9-decen-1-yl hexanoate, hexyl butanoate and pentyl acetate were detected in the early stages of the infection. Styrene, terpinene-4-ol, ethyl hexanoate, ethyl butanoate, ethyl pentanoate and 2-methylpentyl formate constituted the main VOCs emitted during apple fruit decay. Other compounds such as alpha Farnesene and hexyl acetate were common to both healthy and inoculated apples but the peak areas in the healthy apples were well above the peak areas in the inoculated apples. However, these compounds expressed a decline in peak area over time. Apples are stored commercially in sealed stores for months making visual observation for early detection of disease almost impossible. Disease of stored apples are most times only detected at advanced stages when it has become nearly impossible to prevent losses. These discriminatory volatile metabolites detected at early stages of infection are important for early non-visual detection of N. ditissima in stored apples. Further research is recommended to the use of these compounds in early detection of the disease caused by N. ditissima

Caracterización de Phytophthora infestans y mejora genética para la resistencia en patata

La caracterització de Phytophthora infestans, principal patogen de la patata, és d'importància per a la seguretat alimentària. Per això es van realitzar prospeccions en províncies altament productores d'Espanya obtenint 52 aïllats. En aquests aïllats es van identificar mitjançant tècniques moleculars els tipus d'aparellament A1 i A2 mostrant la possibilitat d'aparellament. Els haplotips mitocondrials van indicar la presència de tipus Ia, associat als llinatges clonals US-7 i US-8. Posteriorment, mitjançant la utilització de marcadors SSR es van identificar 12 genotips, entre els quals es troba Blue 13 i les seves variants. L'espectre de virulència va mostrar 17 varietats fisiològiques entre les quals es trobaven aïllats complexos amb 11 gens de virulència. Sobre aquests aïllats complexos es va avaluar a l'acció de 4 fungicides amb diferents matèries actives, sent la Ciazofamida la que va controlar als mateixos. Finalment, dos aïllats agressius es van inocular en espècies silvestres, per identificar fonts de resistència. El programa de millora va permetre seleccionar 33 clons de 2n any amb caràcters agronòmics desitjables i resistents a resistents a P. infestans.La caracterización de Phytophthora infestans, principal patógeno de la patata, es de importancia para la seguridad alimentaria. Por ello se realizaron prospecciones en provincias altamente productoras de España obteniendo 52 aislados. En estos aislados se identificaron mediante técnicas moleculares los tipos de apareamiento A1 y A2 mostrando la posibilidad de apareamiento. Los haplotipos mitocondriales indicaron la presencia de tipo Ia, asociado a los linajes clonales US-7 y US-8. Posteriormente, mediante la utilización de marcadores SSR se identificaron 12 genotipos, entre los que se encuentra Blue 13 y sus variantes. El espectro de virulencia mostró 17 razas fisiológicas entre las que se encontraron aislados complejos con 11 genes de virulencia. Sobre estos aislados complejos se evaluó a la acción de 4 fungicidas con diferentes materias activas, siendo la Ciazofamida la que controló a los mismos. Por último, dos aislados agresivos se inocularon en especies silvestres, para identificar fuentes de resistencia. El programa de mejora permitió seleccionar 33 clones de 2° año con caracteres agronómicos deseables y resistentes a resistentes a P. infestans.The Characterization of Phytophthora infestans, main pathogen of potato, is relevant for food security. For that reason it had made a survey in different places from Spain obtaining 52 isolates. The molecular techniques were first identified the mating types A1 and A2 showing the mating possibility. The presence of type Ia was identified by mitochondrial haplotypes, this type is associated with clonal lineages US-7 and US-8. Subsequently, by using SSR markers were identified 12 genotypes among them Blue 13 and its variants. The virulence spectrum study identified 17 physiological races where there had complex isolates with 11 genes of virulence. These complex isolated were evaluated by 4 fungicide with different active materials, being Cyazofamid who controlled to isolated. Finally, two aggressive isolates were inoculated in wild species, to identify sources of resistance. The improvement program allowed selected 33 clones of 2nd year with desirable traits and resistant to P. infestans

Construction of pathogenic, biologic and genetic bases of the Colombian populations of Rhizoctonia solani AG-3 necessary for the development of management strategies of stem canker and black scurf diseases of potato

Rhizoctonia solani AG-3 Kühn (teleomorph: Thanatephorus cucumeris (Frank) Donk) es un patógeno del suelo importante en cultivos de papa a nivel mundial. Aunque este patógeno es importante en Colombia actualmente no existe información acerca del patógeno y la enfermedad. Esta investigación se realizo utilizando pruebas moleculares y biológicas con el fin de conocer los Grupos de Anastomosis (GA) asociados a síntomas en las principales regiones productoras de papa en Colombia. Adicionalmente la variabilidad genética y su distribución geográfica, así como la respuesta del patógeno a dos temperaturas, a un fungicida y su agresividad sobre plantas de papa fueron evaluadas. Las muestras fueron colectadas en tallos de plantas sintomáticas de papa en campos naturalmente infestados, posteriormente fueron procesadas en el laboratorio y los aislamientos obtenidos se sometieron a diferentes análisis. El GA-3 de R. solani fue el comúnmente asociado a los síntomas en campo. Los aislamientos colectados en diferentes regiones geográficas fueron variables y la variabilidad no está asociada a regiones geográficas, las poblaciones son genéticamente similares mostrando el efecto del flujo de genes en la estructura genética de la población. La evaluación de la respuesta del patógeno a dos temperaturas, la sensibilidad al fungicida thifluzamide y la agresividad en diferentes órganos de las plantas de papa mostraron que los aislamientos de todas las localidades geográficas varían en la respuesta los factores evaluados. Los niveles de costra negra y de chancros variaron entre aislamientos sobre el cultivar de papa evaluado. / Abstract. Rhizoctonia solani AG-3 Kühn (teleomorph: Thanatephorus cucumeris (Frank) Donk) is a main soil-borne pathogen on potato crops around the world. Actually this pathogen is recognized as important in Colombia; however there is no information about the pathogen and the disease. This research was conducted using biological and molecular tests to know the Anastomosis Groups (AG) associated with symptoms in the main producing potato areas in Colombia. Additionally the genetic variability of the isolates and the distribution of variability along the main potato producing areas in Colombia as well as the response of the pathogen to temperatures and fungicides and its aggressiveness on potato plants were tested. The samples were collected from symptomatic stems of potato on naturally infested fields and then were processed in laboratory. The isolates were subject of different analysis. The AG-3 of R. solani was the most common associated to symptoms in fields. The isolates from different geographical populations were highly variable and the variability was not structured geographically. All the populations are genetically similar showing the effect of gene flow in the genetic structure of the populations. The evaluation of the response of the pathogen to two temperatures, the sensitivity to the fungicide thifluzamide and the aggressiveness on different organs of the potato plants showed that the isolates of all the geographical localities vary in the response to the factors evaluated. The levels of black scurf and cankers were low and variable among isolates in the cultivar of potato evaluated.Doctorad

Plant Biodiversity and Genetic Resources

The papers included in this Special Issue address a variety of important aspects of plant biodiversity and genetic resources, including definitions, descriptions, and illustrations of different components and their value for food and nutrition security, breeding, and environmental services. Furthermore, comprehensive information is provided regarding conservation approaches and techniques for plant genetic resources, policy aspects, and results of biological, genetic, morphological, economic, social, and breeding-related research activities. The complexity and vulnerability of (plant) biodiversity and its inherent genetic resources, as an integral part of the contextual ecosystem and the human web of life, are clearly demonstrated in this Special Issue, and for several encountered problems and constraints, possible approaches or solutions are presented to overcome these