Insights into Phytophthora ramorum sporulation: epidemiological and evolutionary implications

Autor: J. A. Garcia Munoz, E. Descals, E. Moralejo
Rok vydání: 2006
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1365-2338
0250-8052
DOI: 10.1111/j.1365-2338.2006.01016.x
Popis: Two aspects on the epidemiology of Phytophthora ramorum are discussed. Firstly, in order to elucidate its spatial scale of dispersal, its modes of asexual sporulation in culture and in planta are examined and compared to those of the also aerially dispersed P. infestans. On agar media, P. ramorum sporangia are slightly sticky, tend to aggregate in clusters, and are not shed into the air even when violently shaken or subjected to strong air humidity changes. After inoculating the underside of leaves from an assortment of Mediterranean woody species, no evidence of any adaptations for wind dispersal was observed. On some hosts, it formed sporangiomata (clusters of sporangia) on the upperside. Our observations agree with previous field research in that P. ramorum is rain-splash rather than wind dispersed, as opposed to P. infestans. Secondly, in Petri dish cultures both species sporulate heavily. However, a steep reduction in sporangial density (sporangia cm-2) was found on leaves of susceptible Mediterranean species for P. ramorum and a progressive one for P. infestans when this was inoculated on leaves of susceptible potato and other members of the Solanaceae. Furthermore, there was a negative correlation between sporangial density and virulence. We propose a similar pattern of a trade-off between spore production and virulence to that observed by Thrall & Burdon (2003) for the Linum-Melampsora plant-pathogen system. Epidemiological and evolutionary implications are discussed. © 2006 OEPP/EPPO.
Databáze: OpenAIRE
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