Suchergebnisse

Las plantas, cultivadas o no, están sujetas como los animales y el ser humano a enfermedades que originan perjuicio en los procesos fisiológicos que determinan su crecimiento y desarrollo. El ataque por enfermedades puede tener carácter devastador o dar lugar a importantes reducciones del rendimiento de los cultivos o de la funcionalidad de dehesas y montes, lo cual les ha conferido y continúa confiriéndoles en la actualidad un papel relevante en la producción de alimentos, fibras y madera, y en la estabilidad de los ecosistemas vegetales. Por ello, durante la historia de la Fitopatología ha constituido un continuo reto para los fitopatólogos desarrollar mediante el estudio, la investigación y la experimentación, estrategias de lucha que hagan posible el control eficiente de las enfermedades de las plantas. A dicho reto se han unido desde hace unas décadas cautelas y pautas legislativas sobre las formas y medios para el control de las enfermedades, que son consecuencia de la preocupación social por la eventual repercusión que éstos pueden tener sobre la salubridad alimentaria y la calidad y preservación del medio ambiente. Dichas cautelas han culminado recientemente en la Directiva 2009/128/CE y el Reglamento (CE) 1107/2009 relativos al uso sostenible y comercialización de productos fitosanitarios, así como al Manejo Integrado y empleo de medios no químicos como estrategia fundamental de lucha contra Enfermedades, Plagas y Malas Hierbas. Consciente de dichos retos, y en correspondencia con su compromiso para promover el estudio de la Fitopatología y la difusión de los avances que se originen de él, la Sociedad Española de Fitopatología (SEF) inicia con esta monografía un programa de publicaciones sobre agentes fitopatógenos y enfermedades que causan, con el objetivo de potenciar la actividad que ha venido desarrollando en este marco. Los Hongos y Oomicetos destacan notablemente entre la variedad de organismos que pueden causar enfermedades en las plantas (i.e., virus, fitoplasmas, bacterias, hongos, nematodos, ...

The integrated management concept is one of the fundamental paradigms that have emerged in crop protection in the last 50 yrs and yet a matter for legislation as exemplified by the European Union that recently has establishes the integrated management as the fundamental procedure for the management of crop diseases, pests and weeds. However, the integrated management is not a panacea for the control of plant diseases. It is an ecology-based approach aiming minimizing damage caused by diseases through 'the combined use of all available disease control measures, either simultaneously or in a sequence, through actions taken prior and after establishing the crop'. In this chapter, we propose and develop a strategy for the integrated management for Fusarium wilts, one of the most devastating and challenging type of diseases impairing agricultural production worldwide,, based on the: (i) use of pathogen-free planting material; (ii) site selection to avoid planting into high risk soils; (iii) reduction or elimination of F. oxysporum inoculum in soil; (iv) use of biocontrol agents for protection of healthy planting material from infection by resident or incoming inoculum subsequent to planting; (v) use of resistant cultivars regardless the level of resistance; and (vi) choice of cropping practices to avoid conditions favouring infection of the plant. The integrated management of Fusarium wilt diseases is difficult because complexities of target pathosystems are overlaid on the inherent complexities of the management strategy itself. Much research is still needed on population biology and genetic diversity in Fusarium wilt pathogens, disease risk prediction, disease-incidence-yield losses relationships, biological control, biotechnological breeding for disease resistance. On top of difficulties pointed out above, the practice of integrated management requires involvement of well-trained professional plant pathologists able to implement the tenets of the concept at the local level, as well as to incorporate into decision-making framework new knowledge and technologies that may be developed from scientific research. As the demand has increased for knowledgeable practitioners capable of integrating multifaceted controls in rigorous IDM programs, institutional support has declined through declining or even vanishing University education in Plant Pathology and the loss of extension-related activities in commercial agriculture. Erosion at the top of the trickle-down structure responsible for knowledge transfer to the field is one of the most serious threats to IDM.

Downy mildew (DM) of opium poppy (Papaver somniferum) caused by Peronospora somniferi is one of the most destructive diseases of this crop due to the systemic nature of infection as compared with local infections caused by Peronospora meconopsidis, the other downy mildew pathogen of this crop. We developed an inoculation method using Peronospora somniferi sporangia as inoculum and demonstrated for the first time that local infection of leaves by sporangia give rise to systemic infections in the plant as well as of seeds. Our results also showed that this inoculation protocol was very effective in reproducing disease symptoms and assessing the resistance response to DM in opium poppy genotypes under field conditions. More interestingly, results indicate that up to 100% of seed samples from some genotypes showing a complete (symptomless) resistant phenotype were infected by the pathogen when seeds were analyzed by a P. somniferi-specific nested-PCR protocol. This latter aspect deserves further attention while breeding opium poppy for resistance to P. somniferi. ; Regional Government of Andalusia (project P10-AGR-6497) to MMB; European Union through the European Regional Development Fund (ERDF). ; Peer reviewed

Host resistance is the most practical, long-term, and economically efficient disease control measure for Verticillium wilt in olive caused by the xylem-invading fungus Verticillium dahliae (Vd), and it is at the core of the integrated disease management. Plant's microbiome at the site of infection may have an influence on the host reaction to pathogens; however, the role of xylem microbial communities in the olive resistance to Vd has been overlooked and remains unexplored to date. This research was focused on elucidating whether in vitro olive propagation may alter the diversity and composition of the xylem-inhabiting microbiome and if those changes may modify the resistance response that a wild olive clone shows to the highly virulent defoliating (D) pathotype of Vd. Results indicated that although there were differences in microbial communities among the different propagation methodologies, most substantial changes occurred when plants were inoculated with Vd, regardless of whether the infection process took place, with a significant increase in the diversity of bacterial communities when the pathogen was present in the soil. Furthermore, it was noticeable that olive plants multiplied under in vitro conditions developed a susceptible reaction to D Vd, characterized by severe wilting symptoms and 100% vascular infection. Moreover, those in vitro propagated plants showed an altered xylem microbiome with a decrease in total OTU numbers as compared to that of plants multiplied under non-aseptic conditions. Overall, 10 keystone bacterial genera were detected in olive xylem regardless of infection by Vd and the propagation procedure of plants (in vitro vs nursery), with Cutibacterium (36.85%), Pseudomonas (20.93%), Anoxybacillus (6.28%), Staphylococcus (4.95%), Methylobacterium-Methylorubrum (3.91%), and Bradyrhizobium (3.54%) being the most abundant. Pseudomonas spp. appeared as the most predominant bacterial group in micropropagated plants and Anoxybacillus appeared as a keystone bacterium in Vd-inoculated plants irrespective of their propagation process. Our results are the first to show a breakdown of resistance to Vd in a wild olive that potentially may be related to a modification of its xylem microbiome and will help to expand our knowledge of the role of indigenous xylem microbiome on host resistance, which can be of use to fight against main vascular diseases of olive. ; This study was funded by project AGL2016-75606-R (Programa Estatal de I+D Orientado a los Retos de la Sociedad from the Spanish Government, the Spanish State Research Agency, and FEDER-EU). MA-M is a recipient of a research fellowship BES-2017-082361 from the Spanish Ministry of Economy and Competitiveness.