DETERMINANTS OF DISEASE EXPRESSION AND SURVIVAL OF INFECTED INDIVIDUAL FRONDS IN WILD POPULATIONS OF MAZZAELLA LAMINARIOIDES (RHODOPHYTA) IN CENTRAL AND SOUTHERN CHILE

This study provides evidence that the expression of a deformative dise ase in wild populations of the red algal host Mazzaella laminarioides is strongly influenced by exogenous factors. This was particularly the case for a population in Matanzas, Chile, whose members developed the symptoms when they grew in a high-infection zone, regardless of their history of susceptibility to the disease. However, our results for be tween locality transplants suggest that a genetic component may be pla ying a role in the expression of the disease. plants transplanted from one locality to another did not reach the same levels of disease expr ession as their indigenous local counterparts. Infectious diseases see m to affect the survival of the infected hosts, an effect that varies depending on the pathogen involved, the season and the locality under consideration. In addition to the direct impacts of the 2 diseases (gr een patch disease caused by Endophyton ramosum and the deformative dis ease associated with Pleurocapsa sp.) affecting Mazzaella laminarioide s, the deformative disease caused an increased susceptibility to grazi ng, which may accelerate the direct negative impact of the pathogen it self.