26
tolerant (Py. orbicularis) and sensitive (L. spicata) algae species, finding that Py.
orbicularis increases GlyI activity and maintains reduced methylglyoxal levels during desiccation. In contrast, L. spicata GlyI activity does not sufficiently increase,
resulting in increased methylglyoxal levels and cellular alterations.
In addition to antioxidant enzyme activity, resurrection plants produce several
antioxidant compounds to reduce ROS levels, including anthocyanin and accessory
pigments. Just as in resurrection plants, algae also produce these compounds during
desiccation stress. An increase in phycobiliproteins such as phycoerythrin, phycocyanin, and allophycocyanin occurs in Py. orbicularis and Gracilaria corticata during
desiccation stress, as evidenced using direct extraction and pigment profiling in
acrylamide gels (Kumar et al. 2011; López-Cristoffanini et al. 2015). These proteins
can both canalize light energy to diminish and neutralize the amount of ROS produced by light excess (Bhat and Madyastha 2001; Romay et al. 2003; Cano-Europa
et al. 2010). Moreover, desiccation in Py. orbicularis results in an overproduction of
the enzyme adenosine 5′-phosphosulfate kinase. This catalyzes the production of
3′-phosphoadenosine 5′-phosphosulfate (Kopriva and Koprivova 2004), which is
involved in the biosynthesis of sulfated polysaccharides (McCandless and Craigie
1979), molecules that present high antioxidant potential (Tannin-Spitz et al. 2005;
Rocha de Souza et al. 2007). Kumar et al. (2011) determined that desiccation- stressed
G. corticata increase ascorbate production, an important antioxidant. This correlates
with the findings of López-Cristoffanini et al. (2015), who showed increases in phosphomannomutase and GDP-D-mannose-3′,5′-epimerase, enzymes involved in ascorbate biosynthesis (Oesterhelt et al. 1996; Valpuesta and Botella 2004). Additionally,
Py. orbicularis also overproduces the stress-inducible pyridoxine biosynthesis protein involved in the synthesis of pyridoxal 5′-phosphate, a form of vitamin B6 with
potent antioxidant functions (Mittenhuber 2001; Raschke et al. 2011).
2.2.5 Perspectives
Mechanisms such as increased antioxidant enzyme activity coupled with an overproduction of antioxidant compounds further explain the dominance displayed by
some algal species in the upper rocky intertidal zones. These mechanisms have also
have been registered in resurrection plants, which evidence conserved mechanisms
of tolerance to water deficit. Specifically, Py. orbicularis demonstrates a wellcoordinated network of mechanisms that successfully scavenge ROS (Fig. 2.2),
Fig. 2.2 (continued) OEE1 plastid oxygen-evolving enhancer 1, P-Gal GDP-l-galactose, PC phycocyanin beta subunit, PE phycoerythrin beta subunit, PGK phosphoglycerate kinase, PMM phosphomannomutase, PPI peptidylprolyl isomerase, Rab11 rab GTPase family 11, RNP RNP
domain- containing protein, RNApol RNA polymerase, RPL35 ribosomal protein L35, RubisCO
ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (chloroplast), SAM
S-adenosylmethionine synthetase, Sar1 small GTP-binding protein Sar1, Sec 7 Sec 7 domain, SLG
S-d-lactoylglutathione, SOR stress-inducible pyridoxine biosynthesis protein SOR, TPI triosephosphate isomerase, TRR thioredoxin reductase, TRX thioredoxin, VDAC voltage-dependent
anion channel
L. Contreras-Porcia et al.
tolerant (Py. orbicularis) and sensitive (L. spicata) algae species, finding that Py.
orbicularis increases GlyI activity and maintains reduced methylglyoxal levels during desiccation. In contrast, L. spicata GlyI activity does not sufficiently increase,
resulting in increased methylglyoxal levels and cellular alterations.
In addition to antioxidant enzyme activity, resurrection plants produce several
antioxidant compounds to reduce ROS levels, including anthocyanin and accessory
pigments. Just as in resurrection plants, algae also produce these compounds during
desiccation stress. An increase in phycobiliproteins such as phycoerythrin, phycocyanin, and allophycocyanin occurs in Py. orbicularis and Gracilaria corticata during
desiccation stress, as evidenced using direct extraction and pigment profiling in
acrylamide gels (Kumar et al. 2011; López-Cristoffanini et al. 2015). These proteins
can both canalize light energy to diminish and neutralize the amount of ROS produced by light excess (Bhat and Madyastha 2001; Romay et al. 2003; Cano-Europa
et al. 2010). Moreover, desiccation in Py. orbicularis results in an overproduction of
the enzyme adenosine 5′-phosphosulfate kinase. This catalyzes the production of
3′-phosphoadenosine 5′-phosphosulfate (Kopriva and Koprivova 2004), which is
involved in the biosynthesis of sulfated polysaccharides (McCandless and Craigie
1979), molecules that present high antioxidant potential (Tannin-Spitz et al. 2005;
Rocha de Souza et al. 2007). Kumar et al. (2011) determined that desiccation- stressed
G. corticata increase ascorbate production, an important antioxidant. This correlates
with the findings of López-Cristoffanini et al. (2015), who showed increases in phosphomannomutase and GDP-D-mannose-3′,5′-epimerase, enzymes involved in ascorbate biosynthesis (Oesterhelt et al. 1996; Valpuesta and Botella 2004). Additionally,
Py. orbicularis also overproduces the stress-inducible pyridoxine biosynthesis protein involved in the synthesis of pyridoxal 5′-phosphate, a form of vitamin B6 with
potent antioxidant functions (Mittenhuber 2001; Raschke et al. 2011).
2.2.5 Perspectives
Mechanisms such as increased antioxidant enzyme activity coupled with an overproduction of antioxidant compounds further explain the dominance displayed by
some algal species in the upper rocky intertidal zones. These mechanisms have also
have been registered in resurrection plants, which evidence conserved mechanisms
of tolerance to water deficit. Specifically, Py. orbicularis demonstrates a wellcoordinated network of mechanisms that successfully scavenge ROS (Fig. 2.2),
Fig. 2.2 (continued) OEE1 plastid oxygen-evolving enhancer 1, P-Gal GDP-l-galactose, PC phycocyanin beta subunit, PE phycoerythrin beta subunit, PGK phosphoglycerate kinase, PMM phosphomannomutase, PPI peptidylprolyl isomerase, Rab11 rab GTPase family 11, RNP RNP
domain- containing protein, RNApol RNA polymerase, RPL35 ribosomal protein L35, RubisCO
ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (chloroplast), SAM
S-adenosylmethionine synthetase, Sar1 small GTP-binding protein Sar1, Sec 7 Sec 7 domain, SLG
S-d-lactoylglutathione, SOR stress-inducible pyridoxine biosynthesis protein SOR, TPI triosephosphate isomerase, TRR thioredoxin reductase, TRX thioredoxin, VDAC voltage-dependent
anion channel
L. Contreras-Porcia et al.