18
et al. 2013; López-Cristoffanini et al. 2015; Fierro et al. 2017). The dehydrated plants
overexpress various tolerance genes related to antioxidant enzymes, heat shock proteins, cytochrome P450, cell wall proteins, and the ATP-binding cassette transporter
proteins (see sections below for molecular description of tolerance mechanisms).
A study by Kumar et al. (2011) in Gracilaria corticata (Gracilariales), collected from
the Veraval coast (Gujarat, India) during low tide, revealed that this seaweed possess
mechanisms similar to Py. orbicularis for regulating desiccation stress-induced damage, in addition to having specific mechanisms for effectively responding to desiccation stress. The adaptive response of G. corticata to desiccation is associated with the
activation of antioxidant enzymes and phycobiliproteins, as well as increased
amounts of specific polyunsaturated fatty acids and of specific soluble and bound
insoluble compounds, such as putrescine and spermine. Moreover, Kumar et al.
(2011) observed the activation of specific isoforms of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (AP), and glutathione peroxidase during desiccation-induced stress. The activation of particular antioxidant compounds
and specific antioxidant enzyme isoforms, as well as an increased presence of polyunsaturated fatty acids, are desiccation-related responses that differ from responses
to other induced abiotic stressors, such as salinity (Kumar et al. 2010).
2.1.3 Species of the Bangiales Order as Models for Studying
Desiccation Stress Tolerance and Seaweed Distribution
in the Intertidal Zone
Taxa of the Bangiales order are an ideal model for studying tolerance mechanisms
to environmental stressors due to worldwide distribution that extends from tropical
to polar seas and from lacustrine to fully marine habitats (Butterfield 2000;
Sutherland et al. 2011). This order is evolutionarily significant as it contains
Bangiomorpha pubescens NJ Butterfield, the oldest taxonomically resolved eukaryote fossil record and the first known record of a sexual and multicellular organism
(Butterfield 2000). While traditional taxonomic studies of the Bangiales order are
based only on very simple and plastic morphologies, recent phylogenetic analyses
based on molecular markers have redefined the frontiers of numerous taxa over the
last 10 years, where several cryptic genera have been discovered and various classical genera have been redefined (e.g., Broom et al. 2002; Brodie et al. 2007; Neefus
et al. 2008; Nelson 2013). Indeed, the worldwide molecular study by Sutherland
et al. (2011) proposed the existence of eight genera of bladed Bangiales, including
Boreophyllum, Clymene, Fuscifolium, Miuraea, Lysithea, Porphyra, Pyropia, and
Wildemania. At a lower taxonomic level, cryptic genetic diversity has also been
found, as particularly evidenced by the redefined genera Porphyra and Pyropia
(Niwa et al. 2009; Broom et al. 2010; Guillemin et al. 2016). Related to this, representative Porphyra and Pyropia specimens have been intensively studied to uncover
physiological ecology patterns of rocky intertidal seaweed communities, the origin
of sexual reproduction, the diversity of reproductive strategies, and the evolutionary
biology of plastids (Blouin et al. 2011; Wang et al. 2013).
L. Contreras-Porcia et al.
et al. 2013; López-Cristoffanini et al. 2015; Fierro et al. 2017). The dehydrated plants
overexpress various tolerance genes related to antioxidant enzymes, heat shock proteins, cytochrome P450, cell wall proteins, and the ATP-binding cassette transporter
proteins (see sections below for molecular description of tolerance mechanisms).
A study by Kumar et al. (2011) in Gracilaria corticata (Gracilariales), collected from
the Veraval coast (Gujarat, India) during low tide, revealed that this seaweed possess
mechanisms similar to Py. orbicularis for regulating desiccation stress-induced damage, in addition to having specific mechanisms for effectively responding to desiccation stress. The adaptive response of G. corticata to desiccation is associated with the
activation of antioxidant enzymes and phycobiliproteins, as well as increased
amounts of specific polyunsaturated fatty acids and of specific soluble and bound
insoluble compounds, such as putrescine and spermine. Moreover, Kumar et al.
(2011) observed the activation of specific isoforms of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (AP), and glutathione peroxidase during desiccation-induced stress. The activation of particular antioxidant compounds
and specific antioxidant enzyme isoforms, as well as an increased presence of polyunsaturated fatty acids, are desiccation-related responses that differ from responses
to other induced abiotic stressors, such as salinity (Kumar et al. 2010).
2.1.3 Species of the Bangiales Order as Models for Studying
Desiccation Stress Tolerance and Seaweed Distribution
in the Intertidal Zone
Taxa of the Bangiales order are an ideal model for studying tolerance mechanisms
to environmental stressors due to worldwide distribution that extends from tropical
to polar seas and from lacustrine to fully marine habitats (Butterfield 2000;
Sutherland et al. 2011). This order is evolutionarily significant as it contains
Bangiomorpha pubescens NJ Butterfield, the oldest taxonomically resolved eukaryote fossil record and the first known record of a sexual and multicellular organism
(Butterfield 2000). While traditional taxonomic studies of the Bangiales order are
based only on very simple and plastic morphologies, recent phylogenetic analyses
based on molecular markers have redefined the frontiers of numerous taxa over the
last 10 years, where several cryptic genera have been discovered and various classical genera have been redefined (e.g., Broom et al. 2002; Brodie et al. 2007; Neefus
et al. 2008; Nelson 2013). Indeed, the worldwide molecular study by Sutherland
et al. (2011) proposed the existence of eight genera of bladed Bangiales, including
Boreophyllum, Clymene, Fuscifolium, Miuraea, Lysithea, Porphyra, Pyropia, and
Wildemania. At a lower taxonomic level, cryptic genetic diversity has also been
found, as particularly evidenced by the redefined genera Porphyra and Pyropia
(Niwa et al. 2009; Broom et al. 2010; Guillemin et al. 2016). Related to this, representative Porphyra and Pyropia specimens have been intensively studied to uncover
physiological ecology patterns of rocky intertidal seaweed communities, the origin
of sexual reproduction, the diversity of reproductive strategies, and the evolutionary
biology of plastids (Blouin et al. 2011; Wang et al. 2013).
L. Contreras-Porcia et al.