Epi-endophytic symbiosis between Laminariocolax aecidioides (Ectocarpales, Phaeophyceae) and Undaria pinnatifida (Laminariales, Phaeophyceae) growing on argentinian coasts

GAUNA, M.C.; PARODI, E.R.; CÁCERES, E.J.

JOURNAL OF APPLIED PHYCOLOGY

SPRINGER

Lugar: Amsterdam; Año: 2008 p. 11 - 18

0921-8971

The present is the first study on epi-endophytic algae on thalli of Undaria pinnatifida growing along Argentinian coasts. The main goal is to describe the nature and the morphology of this symbiosis. Individuals  of Laminariocolax aecidioides were detected in both June and December 2004, growing on U. pinnatifida  sporophytes. In nature, the epi-endophyte were macroscopically observed as dark zones that partially covered  he hosts fronds. L. aecidioides vegetative thalli were irregularly branched uniseriate filaments. The life cycle is described from laboratory cultures started from Patagonian populations. Caryology revealed that the  sporophytic diploid phase presented 16 chromosomes whereas the gametophytic haploid phase presented 8  cromosomes. Isolates made from thalli growing in the interior of infected hosts  developed into filamentous,  branched sporophytes that reproduced by both unispores and plurispores that were produced in unilocular and  plurilocular sporangia, respectively. The results of this paper also allowed us to conclude that L. aecidioides  uses the thalli of U. pinnatifida as a proper substrate. The penetration of endophitic filaments among the host´s cortical cells produced a lateral compression and, finally, their thalli development generated perforations in the  host tissues. The effects of the epiendophytic infection of L. aecidioides on U. pinnatifida are neither severe  or  deleterious.