Pyropia Orbicularis Research Articles

Controlled cultivation of different stages of Pyropia orbicularis (Rhodophyta; Bangiales) from the South Pacific coast

The species of the genus Pyropia have a diplohaplontic life cycle, in which there is a gametophytic phase (n) or blade, and a microscopic sporophytic phase (2n), known as conchocelis, as well as intermediate stages of development. Pyropia species, together with Porphyra species, belong to the group of the most commercialized and produced macroalgae worldwide, mainly due to their high nutritional value and high content of bioactive compounds with antioxidant and anti-inflammatory activity. The interest in cultivating and exploiting this marine resource has increased in recent years; nevertheless, despite the development of cultivation techniques and technologies for these species, there are still difficulties involved in their successful cultivation, mainly related to the great interspecific and intraspecific variability in the required culture conditions. In this work, we study the life cycle development of Pyropia orbicularis, a species endemic to the South Pacific, to determine the effect of abiotic culture parameters, such as the temperature and photoperiod, on the formation and development of early and late life cycle stages, such as conchocelis formation, cochoesporangial filaments, conchospore release and blade growth. Our results demonstrate that the conchocelis phase grew rapidly under 8:16 h (L:D) photoperiod conditions at both 15 °C and 20 °C. The lower temperatures favored the formation of conchosporangia and conchospores; the rate of their development was increased at 15 °C. The development of the blades in the suspended culture system was constant during the experimental period, generating blades of the same color and shape as those from natural populations. Our results reflect the adaptation of P. orbicularis to the seasonal environmental conditions it is exposed to and the importance of maintaining optimal abiotic parameters for the success of its culture. This work is the first to describe the full life cycle development of P. orbicularis under controlled conditions, which has important implications for commercial production.

Health-promoting activities of edible seaweed extracts from Chilean coasts: assessment of antioxidant, anti-diabetic, anti-inflammatory and antimicrobial potential

The aim of this study was to evaluate the antioxidant, antidiabetic, anti-inflammatory and antimicrobial activities of three edible seaweed extracts from Chilean coasts: Pyropia orbicularis, Ulva spp, and Durvillaea antarctica. Seaweed extracts in methanol and 70% acetone were performed to evaluate antioxidant and antidiabetic activities, whereas 60% methanol was used to measure anti-inflammatory and antimicrobial activities. Acetone extracts from D. antarctica had the highest total phenolic content and consequently exhibited the strongest antioxidant activity, while methanol extract of this seaweed presented the highest α-glucosidase inhibition (IC50= 0.004 mg mL-1). In the tests against E. coli and Penicillium sp., the extracts obtained from Ulva spp. were the most effective and exhibited the maximum anti-inflammatory effect against phorbol 12-myristate 13-acetate irritant agent (61.8% inhibition) in mice. Results indicated that all evaluated Chilean seaweed extracts are promising candidates for application in functional foods and in the pharmaceutical industry.

Development of six novel microsatellite markers for the Chilean red alga <i>Pyropia orbicularis</i>

Mariculture of edible Porphyra/Pyropia species, which are cosmopolitan red foliose algae, represent an important source of income for the pharmaceutical and food industries. In Chile, the most common alga of this complex is Pyropia orbicularis (Bangiales, Rhodophyta). Here we report 6 microsatellite markers obtained from P. orbicularis through a genomic library from 10 individuals of the gametophytic phase by next generation (Illumina) sequencing. Polymorphism analyses were done from 10 individuals of the conchocelis phase, revealing an allelic diversity ranging from three to six alleles per locus, and observed heterozygosity (HO) and expected heterozygosity (HE) ranging from 0.200 to 0.995, and 0.250 to 0.610, respectively. A large proportion of genetic variance (61%) in P. orbicularis was among individuals within population, and 39% genetic variance was among populations. Nonetheless, these results should be interpreted with caution; further research using larger sample sizes is required. These polymorphic markers could be useful in future studies on population genetic structure, for conservation and applied purposes.

First approach of characterization of bioactive compound in Pyropia orbicularis during the daily tidal cycle

The red seaweed Pyropia orbicularis is an economic important species that occurs predominantly in the high intertidal zone along the chilean coast where it experiences extreme conditions under daily turning tides. Its gametophytic phase has been demonstrated to have a high desiccation tolerance, both at the genomic and proteomic levels, but studies at the metabolomic level are still lacking. This research aimed at characterizing compounds related to desiccation stress tolerance by performing several phase solid extractions with different solvents. Bioactivity-guided fractionation (antioxidant and antibacterial activities) was made for a more specific characterization. Compounds identification was done using LC-MS/MS. Results showed that P. orbicularis produces different compounds depending on the state of hydration during the tidal cycle. For example, minoxidil was only found under hydration, while vincamine only during desiccation. It was also found that the main antioxidant activity was most likely due to lutein and the antibacterial activity could be mainly attributed to compounds of lipid nature such as phosphatidylethanolamine (PE), phosphatidylserine (PS) and monogalactosyldiacylglycerol (MGDG). These results help to get a better understanding of the stress tolerance mechanisms in P. orbicularis and place it like a potential source of bioactive compounds.

Non-Random Distribution and Ecophysiological Differentiation of Pyropia Species (Bangiales, Rhodophyta) Through Environmental Gradients.

Recently 18 Bangiales seaweed species were reported for the Chilean coast, including Pyropia orbicularis and Pyropia variabilis (large [LM] and green [GM] morphotypes). Porphyra/Pyropia spp. occur mainly in the upper intertidal where desiccation stress is triggered by tidal fluctuations. However, the influence of environmental and ecophysiological variables and seasonal differences on Porphyra/Pyropia (microhabitats) intertidal distributions is unknown. Accordingly, we determined (i) the effect of environmental variables (temperature [T], relative humidity [RH], and photosynthetically active radiation [PAR]) and season on distribution, and (ii) physiological (cellular activity and lipid peroxidation [LPX]) and molecular responses (antioxidant enzymes expression at biochemical and transcript level) to desiccation stress in both Pyropia species and morphotypes (common garden experiment, on flat rocky platforms). Multivariate analyses of coverage and abundance in relation to environmental variables revealed a significant effect of temperature on P.variabilis GM distribution, GM dominating almost exclusively on rocky walls (where lowest PAR and T values but maximum RH were registered). Conversely, Pyropia orbicularis and Pyropia variabilis LM were found in high abundance on flat rocky platforms in summer, LM and GM also dominating flat rocky platforms in winter and spring. LPX and catalase activity did not differed among species in summer, while in winter activity and transcription of cat were higher in P.orbicularis than P.variabilis. Results suggest that tolerance to environmental stresses such as temperature could regulate the occurrence of P.variabilis GM on rocky walls; conversely, abundances of P.variabilis and P.orbicularis on flat rocky platforms would be also regulated by other abiotic and/or biotic factors.

Evaluation of physicochemical composition and bioactivity of a red seaweed (Pyropia orbicularis) as affected by different drying technologies

The red seaweed Pyropia orbicularis was dried using four different drying methods (freeze-, vacuum-, solar-, and convective-drying) to evaluate the effect of the drying method on physicochemical parameters, phytochemical contents, antioxidant activity, and antimicrobial activity. Freeze- and vacuum-drying resulted in dried samples with the highest total amino acids retention. Solar and convective drying resulted in dried samples with the highest polyunsaturated fatty acids retention. All dried seaweed showed a significant decrease (p < .05) in the pigments content and antioxidant activity when compared with fresh samples. With respect to the antimicrobial activity, the methanolic extracts of seaweeds showed antifungal activity but not antibacterial activity. In general, freeze-drying resulted in dried samples with the best overall quality.

Genetic and morphological differentiation of Porphyra and Pyropia species (Bangiales, Rhodophyta) coexisting in a rocky intertidal in Central Chile.

A recent molecular taxonomic study along the Chilean coast (18° S-53° S) described 18 candidate species of bladed Bangiales of which only two were formally described. Few studies focused on local genetic and morphological diversity of bladed Bangiales and attempted to determine their intertidal distribution in contrasting habitats, and none were performed in Chile. To delimit intertidal distributions of genetic species, 66 samples of bladed Bangiales were collected at Maitencillo (32° S) in four zones: a rocky platform, a rocky wall, and two boulders zones surrounded by sandy and rocky bottoms, respectively. These samples were identified based on sequences of the mitochondrial COI and chloroplast rbcL markers. We also collected 87 specimens for morphological characterization of the most common species, rapidly assessing their putative species identity using newly developed species-diagnostic (PCR-RFLP) markers. Eight microscopic and two macroscopic morphological traits were measured. We described and named three of four species that predominate in Maitencillo (including Pyropia orbicularis): Pyropia variabilis Zapata, Meynard, Ramírez, Contreras-Porcia, sp. nov., Porphyra luchea Meynard, Ramírez, Contreras-Porcia sp. nov., and Porphyra longissima Meynard, Ramírez, Contreras-Porcia, sp. nov. With the exception of Po. longissima restricted to boulders surrounded by sandy bottom, and a morphotype of Py. variabilis restricted to rocky walls, the other species/morphotypes have overlapping intertidal distributions. Except for Po. longissima, which is clearly differentiated morphologically (longest and thinnest blades), we conclude that morphology is not sufficient to differentiate bladed Bangiales. Our findings underscore the importance of refining our knowledge of intrinsic and environmental determinants on the distribution of bladed Bangiales.

An edible red seaweed (Pyropia orbicularis): influence of vacuum drying on physicochemical composition, bioactive compounds, antioxidant capacity, and pigments

Drying kinetics, proximate composition, dietary fiber, total phenolic compounds, pigments, amino acid profile, and antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity) of a red edible seaweed (Pyropia orbicularis) subjected to vacuum drying at five temperatures (40–80 °C) were evaluated. The experimental drying curves were satisfactorily fitted to the Weibull model. The total dietary fiber (TDF) of this seaweed presented a value of 64.37 g (100 g)−1 d.m. The ratio IDF:TDF was 81.1%. The values for protein ranged between 22.34 and 24.92 g (100 g)−1 d.m. in dried seaweed, and His, Thr, and Pro were the most abundant amino acids. The chlorophyll a content was higher than that for chlorophyll b. Total phenolic content (TPC), phycoerythrin and phycocyanin contents, and carotenoid content as well as antioxidant capacity showed an increase at 70 °C. Moreover, at 70 °C, ΔE presented a value of 15.66. Correlations between the TPC and DPPH values (r 2 = 0.899) as well as lightness and hue angle (r 2 = 0.776) were found during food drying. This work provides important information about the chemical composition and nutraceutical properties of the Chilean edible red seaweed, P. orbicularis.

Expression profile of desiccation tolerance factors in intertidal seaweed species during the tidal cycle.

The transcriptional modulation of desiccation tolerance factors in P. orbicularis explains its successful recuperation after water deficit. Differential responses to air exposure clarify seaweed distribution along intertidal rocky zones. Desiccation-tolerant seaweed species, such as Pyropia orbicularis, can tolerate near 96% water loss during air exposure. To understand the phenotypic plasticity of P. orbicularis to desiccation, several tolerance factors were assessed by RT-qPCR, Western-blot analysis, and enzymatic assays during the natural desiccation-rehydration cycle. Comparative enzymatic analyses were used to evidence differential responses between P. orbicularis and desiccation-sensitive species. The results showed that during desiccation, the relative mRNA levels of genes associated with basal metabolism [trehalose phosphate synthase (tps) and pyruvate dehydrogenase (pdh)] were overexpressed in P. orbicularis. Transcript levels related to antioxidant metabolism [peroxiredoxin (prx); thioredoxin (trx); catalase (cat); lipoxygenase (lox); ferredoxin (fnr); glutathione S-transferase (gst)], cellular detoxification [ABC transporter (abc) and ubiquitin (ubq)], and signal transduction [calmodulin (cam)] increased approximately 15- to 20-fold, with the majority returning to basal levels during the final hours of rehydration. In contrast, actin (act) and transcription factor 1 (tf1) transcripts were down-regulated. ABC transporter protein levels increased in P. orbicularis during desiccation, whereas PRX transcripts decreased. The antioxidant enzymes showed higher specific activity in P. orbicularis under desiccation, and sensitive species exhibited enzymatic inactivation and scarce ABC and PRX protein detection following prolonged desiccation. In conclusion, the reported findings contribute towards understanding the ecological distribution of intertidal seaweeds at the molecular and functional levels.

Methylglyoxal metabolism in seaweeds during desiccation

In primary producers, diverse stressors cause an over-production of methylglyoxal (MG), which is principally detoxified by glyoxalase I (GLO1) activity. A recent proteomic study found that GLO1 was up-regulated during natural desiccation in the red seaweed Pyropia orbicularis, which inhabits the upper intertidal rocky zone and compared to other species, is highly tolerant to air exposure. To better understand and determine differential responses to desiccation stress, this study evaluated MG concentration and GLO1 activity in two species with contrasted vertical distribution, P. orbicularis and Lessonia spicata (lower distribution). Results showed that P. orbicularis successfully scavenges MG via increased GLO1 activity during desiccation. In contrast, GLO1 activity in L. spicata did not increase during desiccation, resulting in MG overproduction. This study is the first to quantify MG and GLO1 levels in seaweeds during natural stress, and partly explain the mechanisms by which P. orbicularis is dominant in the upper rocky intertidal zone.

Role of abscisic acid (ABA) in activating antioxidant tolerance responses to desiccation stress in intertidal seaweed species.

The hormone ABA regulates the oxidative stress state under desiccation in seaweed species; an environmental condition generated during daily tidal changes. Desiccation is one of the most important factors that determine the distribution pattern of intertidal seaweeds. Among most tolerant seaweed is Pyropia orbicularis, which colonizes upper intertidal zones along the Chilean coast. P. orbicularis employs diverse mechanisms of desiccation tolerance (DT) (among others, e.g., antioxidant activation, photoinhibition, and osmo-compatible solute overproduction) such as those used by resurrection plants and bryophytes. In these organisms, the hormone abscisic acid (ABA) plays an important role in regulating responses to water deficit, including gene expression and the activity of antioxidant enzymes. The present study determined the effect of ABA on the activation of antioxidant responses during desiccation in P. orbicularis and in the sensitive species Mazzaella laminarioides and Lessonia spicata. Changes in endogenous free and conjugated ABA, water content during the hydration-desiccation cycle, enzymatic antioxidant activities [ascorbate peroxidase (AP), catalase (CAT) and peroxiredoxine (PRX)], and levels of lipid peroxidation and cell viability were evaluated. The results showed that P. orbicularis had free ABA levels 4-7 times higher than sensitive species, which was overproduced during water deficit. Using two ABA inhibitors (sodium tungstate and ancymidol), ABA was found to regulate the activation of the antioxidant enzymes activities during desiccation. In individuals exposed to exogenous ABA the enzyme activity increased, concomitant with low lipid peroxidation and high cell viability. These results demonstrate the participation of ABA in the regulation of DT in seaweeds, and suggest that regulatory mechanisms with ABA signaling could be of great importance for the adaptation of these organisms to dehydration.

The bladed Bangiales (Rhodophyta) of the South Eastern Pacific: Molecular species delimitation reveals extensive diversity.

A molecular taxonomic study of the bladed Bangiales of the South Eastern Pacific (coast of Chile) was undertaken based on sequence data of the mitochondrial COI and chloroplast rbcL for 193 specimens collected from Arica (18°S) in the north to South Patagonia (53°S) in the south. The results revealed for the first time that four genera, Porphyra, Pyropia, Fuscifolium and Wildemania were present in the region. Species delimitation was determined based on a combination of a General Mixed Yule Coalescence model (GMYC) and Automatic Barcode Gap Discovery (ABGD) coupled with detection of monophyly in tree reconstruction. The overall incongruence between the species delimitation methods within each gene was 29%. The GMYC method led to over-splitting groups, whereas the ABGD method had a tendency to lump groups. Taking a conservative approach to the number of putative species, at least 18 were recognized and, with the exception of the recently described Pyropia orbicularis, all were new to the Chilean flora. Porphyra and Pyropia were the most diverse genera with eight 'species' each, whereas only a 'single' species each was found for Fuscifolium and Wildemania. There was also evidence of recently diverging groups: Wildemania sp. was distinct but very closely related to W. amplissima from the Northern Hemisphere and raises questions in relation to such disjunct distributions. Pyropia orbicularis was very closely related to two other species, making species delimitation very difficult but provides evidence of an incipient speciation. The difference between the 'species' discovered and those previously reported for the region is discussed in relation to the difficulty of distinguishing species based on morphological identification.

Identification of proteins involved in desiccation tolerance in the red seaweed Pyropia orbicularis (Rhodophyta, Bangiales).

Extreme reduction in cellular water content leads to desiccation, which, if persistent, affects the physiology of organisms, mainly through oxidative stress. Some organisms are highly tolerant to desiccation, including resurrection plants and certain intertidal seaweeds. One such species is Pyropia orbicularis, a rhodophycean that colonizes upper intertidal zones along the Chilean coast. Despite long, daily periods of air exposure due to tides, this alga is highly tolerant to desiccation. The present study examined the proteome of P. orbicularis by 2DE and LC-MS/MS analyses to determine the proteins associated with desiccation tolerance (DT). The results showed that, under natural conditions, there were significant changes in the protein profile during low tide as compared to naturally hydrated plants at high tide. These changes were mainly in newly appeared proteins spots such as chaperones, monodehydroascorbate reductase, and manganese superoxide dismutase, among others. Previously undescribed proteins under desiccation conditions included phycobiliproteins, glyoxalase I, and phosphomannomutase. These changes evidenced that several physiological responses involved in DT are activated during low tide, including decreased photosynthetic activity, increased antioxidant capacity, and the preservation of cell physiology by regulating water content, cell wall structure, and cell volume. Similar responses have been observed in resurrection plants and bryophytes exposed to desiccation. Therefore, the coordinated activation of different desiccation tolerance pathways in P. orbicularis could explain the successful biological performance of this seaweed in the upper intertidal rocky zones.

Pyropia orbicularis sp. nov. (Rhodophyta, Bangiaceae) based on a population previously known as Porphyra columbina from the central coast of Chile

A new species of bladed Bangiales, Pyropia orbicularis sp. nov., has been described for the first time from the central coast of Chile based on morphology and molecular analyses. The new species was incorrectly known previously as Porphyra columbina (now Pyropia columbina), and it can be distinguished from other species of Pyropia through a range of morphological characteristics, including the shape, texture and colour of the thallus, and the arrangement of the reproductive structures on the foliose thalli. Molecular phylogenies based on both the mitochondrial COI and plastid rbcL gene regions enable this species to be distinguished from other species within Pyropia. P. orbicularis sp. nov. belongs to a well-supported clade of Pyropia from the southern oceans that include specimens from the South Pacific (North, South, Chatham, Stewart, Auckland, and Campbell Island, New Zealand, New South Wales, and Macquarie Island, Australia) including P. columbina and P. plicata. Within this clade, the highest sequence identity was observed between Pyropia orbicularis sp. nov. and Pyropia sp. FIC from the Falkland Islands.