Mixed approach on Chroodactylon ornatum (Stylonematophyceae) tolerance to hyposalinity: growth, photosynthetic performance and carbohydrate analysis

GABRIELA LOGORIO; DAGLIO, YASMIN; CARLOS STORTZ; ROMERO JUAN MANUEL; CECILIA RODRIGUEZ

PHYCOLOGIA

INT PHYCOLOGICAL SOC

Lugar: Lawrence; Año: 2021 vol. 61 p. 16 - 26

0031-8884

Chroodactylon ornatum is a cosmopolitan non-Florideophycean red alga of a simple24 morphology, generally described as an euryhaline species. Herein, we compared the25 response of a marine strain under exposure to different salinities (3, 7.5, 15 and 30 psu)26 through the analyses of growth, morphology, chlorophyll a fluorescence, Floridean starch27 properties, and mucilage composition. In 3 psu, the cultures consisted of solitary cells28 whereas the typical pseudofilamentous morphology of increasing length was found at29 higher salinities. The species grew in the whole range of salinities, although growth30 response together with photosynthetic efficiency were maximum in full seawater. The31 maximum relative electron transport rate (rETR) was significantly lower under hyposaline32 conditions, concomitant with the increase in photophysical decay but not in non33 photochemical quenching of chlorophyll fluorescence (NPQ). Higher phycocyanin content34 at the highest salinity tested (30 psu) could be related to a more efficient energy transfer to35 the reaction centre. The amylopectin:amylose ratios were higher in 7.5 and 30 psu. Agarans36 extracted at different salinities showed similar sulfation degrees, but there was an increase37 in xylose content in the mucilage from lower salinities. This could be related to a change in38 physical properties of the sheath polysaccharide, yielding a polymer with lower gelling39 capacity which hampered the formation and/or length of pseudofilaments.