Stress metabolite pattern in the eulittoral red alga Pyropia plicata (Bangiales) in New Zealand – mycosporine-like amino acids and heterosides

Abstract

Intertidal rocky shore ecosystems are affected by steep environmental gradients such as fluctuating solar irradiation and salinity along the marine-terrestrial interface. The eulittoral red alga Pyropia plicata (Bangiales) is endemic and abundant to coastal regions of New Zealand and almost unstudied in terms of ecophysiological performance under radiation and salinity stress. Therefore, the acclimation potential of this species against enhanced ultraviolet radiation (UVR) and osmotic stress was evaluated in a combination of field and laboratory experiments with an emphasis on stress metabolite concentrations (UV-sunscreens, organic osmolytes). Samples of P. plicata were collected at the same site in the intertidal zone of Wellington, New Zealand over three seasons (April-November 2016) and used in independent UV and salt stress experiments under controlled conditions. The mycosporine-like amino acids (MAA) shinorine and porphyra-334 were the quantitatively dominant UVsunscreen compounds, and the total concentrations varied over the year between 5 and 14 mg g −1 dry weight (DW), but neither UVR nor PAR had a significant impact on the total or individual MAA concentrations. A UV radiation stress experiment was conducted, but the total MAA concentrations of 6-8 mg g −1 DW did not change, neither did the contents of shinorine (~3 mg g −1 DW) nor that of porphyra-334 (4-5 mg g −1 DW). This suggests, that P. plicata has sufficiently high UV-sunscreen amounts and hence does not respond to changes in UV radiation. Pyropia plicata contained three heterosides (floridoside, D-and L-isofloridoside), which act as organic osmolytes. Seasonally the total concentrations of these compounds varied between 203 and 1226 mmol kg −1 DW, with L-isofloridoside quantitatively dominating all samples. A salt stress experiment showed an increase in the total heteroside concentrations in P. plicata with increasing salinities. However, floridoside was the most upregulated heteroside under hypersaline conditions indicating its key role in osmotic acclimation. Our data indicate that P. plicata always contains various stress metabolites in consistently high concentrations which mitigate against environmental changes typical of the intertidal zone of New Zealand.

Quantitative and Qualitative HPLC Analysis of Mycosporine-Like Amino Acids Extracted in Distilled Water for Cosmetical Uses in Four Rhodophyta

“…This species has porphyra-334 as the dominant MAA, and in minor concentrations, shinorine, palythine, asterina-330, and palythinol. It belongs to the Order Bangiales, which has the highest MAA concentration [17,46,47]. To our knowledge, it is the first time in the literature in which myricetin, a flavonoid found in several foods, has been detected in one species of the Family Gracilariaceae.…”

Seasonal Variation of Mycosporine-Like Amino Acids in Three Subantarctic Red Seaweeds

“…Both species exhibited a significant increase in the concentration of MAAs coinciding with the increase in underwater radiation during sea ice breakup in summer [49]. However, although a seasonal variation in the MAA concentration was reported in the seaweed Pyropia plicata from New Zealand, the increased total MAA content was not correlated with solar radiation [18]. In fact, the authors observed that fronds collected from April to August (autumn-winter period) exhibited the highest MAA content, while fronds collected from August to November (spring) showed a strong decrease in MAA content.…”

“…Additionally, porphyra-334 is the quantitatively most important MAA in N. fastigiata at over 60% in all seasons, except in winter, with palythinol between 15% and 40%. The presence of porphyra-334 as the main component is reported in species that preferentially are often exposed to high solar radiation and grow in the upper littoral to supralittoral zones [16,18,19]. On the other hand, N. fastigiata collected during summer in Valdivia (Chile) exhibited higher MAA content (3.8 mg g -1 of dried mass weight) and different composition as follows: porphyra-334 (80%), shinorine (10%), and palythinol, asterina-330, palythine and mycosporine-glycine with less than 4% each [17].…”

“…The accumulation of MAAs in seaweeds varies, depending on the species, location, and environment in which they are growing [15][16][17], with concentrations up to 14 mg g −1 dry weight [8,18]. MAAs content in seaweeds has been reported at different water depths [16] and geographical areas [15,16,19], and, in general, the highest MAA content often correlates with the degree of exposure to solar radiation [15].…”

“…Additionally, usujirene (λ max at 357 nm) and catenelline (λ max at 334 nm) have been reported in a few species, such as Palmaria palmata, Porphyra yezoensis, Gracilaria tenuifrons, and Catenella repens [28,29]. Advances in technology have revealed new MAAs, not only in seaweeds but also in different marine and terrestrial organisms [18,19,30,31].…”