Integrated Management of Fusarium Wilt Diseases

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

The Fusarium oxysporum f. sp. ciceris/Cicer arietinum pathosystem: a case study of the evolution of plantpathogenic fungi into races and pathotypes

The use of resistant cultivars is one of the most practical and costefficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident. [Int Microbiol 2004; 7(2):95–104

Etiología, importancia y distribución de la seca del garbanzo en el valle del Guadalquivir

La «Seca» o «Fusariosis» del garbanzo (Cicer arietinum, L.)> fue señalada por algunos autores como la enfermedad más importante del cultivo en Andalucía, atribuyéndole importantes pérdidas de cosecha. Sin embargo, el conocimiento en nuestro país sobre su etiología, epidemiología y lucha era prácticamente inexistente, salvo por investigaciones preliminares que indicaron la posibilidad de que la «Fusariosis» incluyera un complejo de enfermedades, que denominamos Marchitez y Podredumbre de Raíz (MPR). Los objetivos generales de las investigaciones incluidas en este trabajo fueron determinar la importancia y distribución de la MPR en el valle del Guadalquivir y su naturaleza etiológica y sintomatológica. Durante 1979 a 1981, se realizaron prospecciones sistemáticas en 108 campos de garbanzo en la Campiña de Córdoba y Sevilla, con un total de más de 1.300 ha., en las que se efectuaron observaciones sobre la sintomatología, incidencia y severidad de los ataques de la MPR. Plantas afectadas con los síntomas característicos se muestrearon para completar las descripciones sintomatológicas de campo y aislar en cultivo puro e identificar los posibles agentes asociados. La patogenicidad de los organismos consistentemente aislados se investigó en inoculaciones con suelo infestado artificialmente, o por inmersión de raices o cultivo de plantas, en una suspensión de inoculo. En suelo infestado con aislamiento patogénicos de Fusarium oxysporum y F. solani, se investigó lá susceptibilidad a ellos de once especies de leguminosas cultivadas, así como las diferencias en patogenicidad para varios cultivos de garbanzo. Cinco complejos sintomatología», amarilleamiento, marchitez, podredumbre seca de raíz, enanismo amarillento y clorosis, se identificaron asociados con la MPR del garbanzo. Todos ellos estuvieron uniformemente distribuidos en la campiña de Córdoba y Sevilla, siendo amarilleamiento y marchitez los más importantes. Tres especies fúngicas, F. oxysporum, F. solani y Macrophomina phaseolina, se aislaron consistentemente de plantas afectadas de los diferentes complejos sintomatológicos y resultaron patogénicos sobre garbanzo en inoculaciones artificiales. Los aislamientos de F. oxysporum fueron clasificados en tres grupos por características morfofisiológicas y patogénicas, caracterizándose, principalmente, por el tipo de síntoma que causaron: marchitez vascular, amarilleamiento vascular y amarilleamiento no vascular con lesiones necróticas corticales en el cuello y raíz. Los dos primeros grupos mostraron especificidad patogénica para garbanzo, por lo que pueden ser considerados como F. oxysporum f. sp. ciceri. La patogenicidad diferencial de ambos grupos sobre cultivares de garbanzo indica que petenecen a diferentes razas fisiológicas. F. solani causó amarilleamiento y podredumbre negra de cuello y raíz, existiendo diferencias morfofisiológicas y de patogenicidad entre aislamientos. Uno de los más virulentos fue identificado como F. eumartii. Los aislamientos de F. solani y F. eumartii resultaron patogénicos sobre garbanzo, haba (Vicia faba L.), guisante (Pisum sativum L.), lenteja (Lens escuelenta Moench.), Lupinus albus, L. angustifolius, L. luteus y L. mutabilis, por lo que rigurosamente no pueden ser caracterizados como alguna de las formas especializadas conocidas, aunque por la reacción observada parecen mejor adaptados a garbanzo, haba y guisante que a las restantes especies. M. phaseolina causó amarilleamiento y podredumbre seca de cuello y raíz. Las infecciones en inoculaciones artificiales fueron mas severas a altas temperaturas y bajo contenido de agua en el suelo, confirmando asi las observaciones de campo. Nuestros resultados señalan a F. oxysporum como agente de la marchitez y del amarilleamiento vasculares, a F. solani como agente del amarilleamiento no vascular asociado con podredumbre negra de cuello y raíz y a M. phaseolina como agente de la podredumbre seca de raíz; si bien, en el complejo amarilleamiento estuvieron implicadas las tres especies fúngicas, así como factores abióticos. Nuestras observaciones indican, asimismo, que el enanismo amarillento puede ser causado por el virus del enrollado de las hojas del guisante (PLRV), aunque otros virus pueden estar implicados, y que la clorosis resulta de una deficiencia férricaSeveral authors have considered the «Seca or fusariosis» disease as the most important disease that causes severe losses of seed yield of chickpea (Cicer arietinum L.) in Andalucía. Nevertheless, there is little knowledge of the etiology, epidemiology and control of that disease, except for some preliminary research which indicated that «Seca» might include a disease complex hereafter named Will and Root Rot (WRR). The objetives of the present study were to determine the etiology, symptomatology, importance and distribution of WRR of chickpeas in the Guadalquivir Valley (Southern Spain). Systematic disease surveys were carried out in the Cordoba and Sevilla provinces of Andalucía, including 108 chickpea fields and 1.300 ha. Observations were made on symptomatology, incidence and severity of WRR attacks. Samples of affected plants were used for further observations and isolations. Pathogenicity of the fungi which were isolated was investigated in artificially infested soil or by dipping the roots or growing plants in a inoculum suspension. Differential pathogenicity to chickpea cultivars and pathogenicity to eleven legume species were investigated in soil artificially infested with isolates of Fusarium oxysporum and F. solani. Five symptom complexes were found associated with WRR attacks: Will, Yellowing, Dry Root Rot, Yellow Stunt and Chlorosis. All symptom complexes were widely and uniformly distributed in Cordoba and Sevilla provinces, but Will and Yellowing cxcurred with higher prevalence, incidence and severity. F. oxysporum, F. solani and Macrophomina phaseolina, were consistently isolated from plants affected by the various symptom complexes. Isolates of those fungi were found to be pathogenic to chickpea in artificial inoculation experiments. Three groups of F. oxysporum isolates were distinguished according to morphological and pathogenic characteristics. Isolates of the different groups caused either vascular will, vascular yellowing, or nonvascular yellowing along with cortical necrotic lesions of collar and root. Isolates inducing vascular wilt or yellowing showed pathogenic specialization to chickpea and may be consideres as F. oxysporum f. sp. ciceri. Those isolates also showed differential pathogenicity to chickpea cultivars, indicating that they belong to different pathogenic races. Isolates of F. solani induced foliar yellowing and black collar and root rot, but differed in morpho-physiological characteristics and virulence. One of the most virulent isolates of F. solani induced foliar yellowing and black collar and root rot, but differed in morpho-physiological characteristics and virulence. One of the most virulent isolates of F. solani was further identified as F. eumartii. Isolates of F. solani and F. eumartii were pathogenic to chickpea, faba bean (Vicia faba L.). pea (Pisum sativum L.), lentil (Lens esculenta Moench), Lupinus albus L., L. angustifolius L., L. luteus L. and L. mutabilis Sweet., and therefore cannot be considered as belonging to any of the known formae speciales of F. solani. Nevertheless, as indicated by the severity of disease reactions observed, those isolates seem to be more adapted to chickpea, faba bean and pea than to any of the other species. M. phaseolina induced yellowing and dry collar and root rot. Infections by this pathogen in artificial inoculations were most severe at high temperatures and low soil water content, thus confirming field observations on incidence and severity of the disease. Our results indicate that F. oxysporum, F. solani and M. phaseolina are, respectively, the agents of Vascular Will and Yellowing, Non-Vascular Yellowing and Black Collar and Root Rot, and Dry Root Rot, However, those three species as well as abiotic factors were involved in the etiology of the Yellowing symptom complex in the field. Also, our observations in the field indicate that the Chlorosis complex is due to an iron deficiency, and that the Yellow Stunt symptom complex might be induced by pea leaf roll virus, although other plants viruses could be involved as well

Ediacaran Obduction of a Fore-Arc Ophiolite in SW Iberia: A Turning Point in the Evolving Geodynamic Setting of Peri- Gondwana

The Calzadilla Ophiolite is an ensemble of mafic and ultramafic rocks that represents the transition between lower crust and upper mantle of a Cadomian (peri-Gondwanan) fore arc. Mapping and structural analysis of the ophiolite demonstrates that it was obducted in latest Ediacaran times, because the Ediacaran-Early Cambrian sedimentary series (Malcocinado Formation) discordantly covers it. The ophiolite and emplacement-related structures are affected by Variscan deformation (Devonian-Carboniferous), which includes SW verging overturned folds (D1) and thrusts (D2), upright folds (D3), extensional faults (D4), and later faults (D5). These phases of deformation are explained in the context of Variscan tectonics as the result of the progressive collision between Gondwana and Laurussia. Qualitative unstraining of Variscan deformation reveals the primary geometry of Ediacaran-Cambrian structures and uncovers the generation of east verging thrusts as responsible for the primary obduction of the Calzadilla Ophiolite. Restoration of planar and linear structures associated with this event indicates an Ediacaran, east directed obduction of the ophiolite, that is, emplacement of the Cadomian fore arc onto inner sections of the northern margin of Gondwana. According to regional data, the obduction separates two extension-dominated stages in the tectonic evolution of the African margin of northern Gondwana preserved in southern Europe. Preobduction extension brought about the onset and widening of fore-arc and back-arc basins in the external part of the continent, while postobduction extension facilitated the formation of extensional migmatitic domes, an oceanward migration of back-arc spreading centers across peri-Gondwana, and the eventual opening of a major basin such as the Rheic Ocean

To succeed as youth athlete: Is it the dead end in track and field?

It is reasonable to believe that a young athlete who succeeds in a World Youth Championship, will also be successful as a senior athlete. To determine the percentage of success of all World Youth Championship finalists who also became finalists in a subsequent senior World Championship, considering all athletes and events at World Athletics Championships. This study analyzed the eight male and eight female finalists of all the events conducted at the World Athletics World Youth Championship from 1999 to 2009, who also became finalists at the World Athletics World Championship from 2001 to 2011. Percentage of success was calculated for track and field events, for male, female, and both. For all the events, from 1759 finalists in a World Youth Championship only 83, representing 4.72%, were also finalists in a World Championship in 2001, 2003, 2005, 2007, 2009, or 2011. Of those 83 athletes, 45 were males and 38 were female. A low rate of success was found. These results were discussed including injuries, early specialization, biological maturation, and/or overtraining, as possible factors related to this low rate of success

Purification and characterization of a hygromycin B phosphotransferase from Streptomyces hygroscopicus

4 pages, 4 figures, 1 table, 20 references.A hygromycin B phosphotransferase activity from Streptomyces hygroscopicus has been highly purified by ammonium sulphate fractionation followed by affinity column chromatography through Sepharose-6B- hygromycin-B.The combined active fractions showed a singleprotein band (41 kDa) when subjected to polyacryl- amide gel electrophoresis in the presence of sodium dodecyl sulphate. When gel electrophoresis was performed under non-denaturing conditions, the single protein band promoted in situ phosphorylation of hygromycin B, indicating that this protein corresponded to the purified hygromycin B phosphotransferase. The enzyme has been purified 236-fold and approximate Km values of 0.56 pM and 36.4 pM for hygromycin B and ATP, respectively, were deduced.This research was supported by grants from the Comisión Asesora de Investigación Científica y Técnica (6131165 and 497) and by an institutional grant from the Fondo de Investigaciones Sanitarias to the Centro de Biología Molecular. M. Zalacaín holds a fellowship from the Consejo Superior de Investigaciones Científicas.Peer reviewe

Las enfermedades de las plantas: impactos, amenazas y control

Las enfermedades reducen significativamente la cosecha agrícola alcanzable y los productos cosechados pueden ser vehículo de micoto-xinas y patógenos humanos. En España, 30 enfermedades afectan gra-vemente a cultivos estratégicos y durante los últimos 25 años se han introducido al menos 49 nuevos patógenos que inciden gravemente sobre aquéllos. La introducción de patógenos exóticos, la homogeneidad gené-tica de los cultivos y la intensificación en el manejo de éstos propician la emergencia y re-emergencia de enfermedades que constituyen nuevas amenazas para la sanidad vegetal. Afrontar estas amenazas requiere mejoras en la investigación científica y translacional, promover la forma-ción universitaria especializada, y una profesión en la Medicina de los Vegetales que sirva a la producción agrícola como la profesión Veterina-ria sirve a la sanidad animalPlant diseases significantly reduce attainable crop yields and harvest products can be contaminated with mycotoxins and human pathogens. In Spain, 30 diseases severely affect strategic crops and at least 49 new pathogens have been introduced during the last 25 years that are addi-tional threats for those crops. Exotic pathogens, crop genetic homogeneity and intensive crop management promote the emergence and reemergence of plant diseases that are new threats for crops health and yield. In order to counteract these new threats, there is a need of improv-ing the scientific and translational research, foster education in Plant Pathology and establishing Plant Medicine profession that serves agricul-ture as Veterinary Science serves animal healt