Multidisciplinary approach to describe Trebouxia diversity within lichenized fungi Buellia zoharyi from the Canary Islands

Abstract

[eng] The Canary Islands are famous for their extraordinary biodiversity; however, lichenized algae have only been studied partially. Buellia zoharyi is a circum-Mediterranean/Macaronesian species that usually occurs in semi-arid areas of theMediterranean, but occasionally some interesting communities of this species grow on basaltic lava flows in Lanzarote, Fuerteventura and Tenerife. Those three locations showed similar ecological conditions, but different mean annual temperatures. Here we applied a multidisciplinary approach to describe microalgae diversity from B. zoharyi covering the entire described range of distribution in the Canary Islands. Photobionts were characterized in symbiosis using molecular and microscopic techniques. Different Trebouxia spp. were detected as primary photobiont in each island (Trebouxia cretacea-Fuerteventura, T. asymmetrica-Lanzarote and Trebouxia sp. `arnoldoi´-Tenerife). Coexistence of various Trebouxia spp. within a thallus were detected by using specific primers-PCR. Those three photobionts were isolated and cultured under laboratory conditions. Different phytohormone profiles were obtained in the isolated strains which suggest different internal signalling needs. In addition, we characterized the response of the isolated strains to different temperatures using chlorophyll fluorescence. T. asymmetrica did not modify their Fv/fm values with respect to temperature acclimation. In contrast, Trebouxia sp. `arnoldoi’and T. cretacea were more sensitive to changes in growing temperature decreasing Fv/fm at 17 °C. Our results indicate that B. zoharyi is flexible regarding the photobiont choice depending on the region, and suggest that bioclimatic factors could influence the myco/photobiont association patterns.