Chemotaxonomic Study of Bostrychia spp. (Ceramiales, Rhodophyta) Based on Their Mycosporine-Like Amino Acid Content

Abstract

This study presents a chemotaxonomic investigation of the genus Bostrychia through the quantitation of the major mycosporine-like amino acids (MAAs). The presence of some cryptic species had been suggested in the B. moritziana/B. radicans complex and MAA-profiling in respective samples revealed different chemotypes within this species complex. Another possibly polyphyletic species is Bostrychia simpliciuscula; previous molecular phylogenetic analyses showed four genetic lineages within this species, one of which was recently distinguished as a new species. Phytochemical profiling of those samples used for DNA analyses revealed four different chemotypes, corresponding to the above four lineages and it supports the re-circumscription of the other three B. simpliciuscula lineages. Therefore, mycosporine-like amino acids are considered as suitable chemotaxonomic markers for the reassessment of the classification of B. simpliciuscula. The determination of the MAA patterns in these algae was possible after developing and validating a suitable high-performance liquid chromatography–diode array detector (HPLC-DAD) method.

Analysis of the Mycosporine-Like Amino Acid (MAA) Pattern of the Salt Marsh Red Alga Bostrychia scorpioides

“…In contrast to other Bostrychia spp. such as B. calliptera and B. simpliciuscula, which are reported to be polyphyletic and show distinct differences in their MAA composition [11,12], no qualitative difference was found in the MAA pattern of the monophyletic species B. scorpioides.…”

“…Compared to all other Bostrychia spp., which are completely absent in Europe, B. scorpioides occupies intertidal habitats of the European Atlantic coast, and shows a unique MAA composition, producing none of the common MAAs such as porphyra-334, palythinethreonine, aplysiapalythine A, asterina-330 or shinorine, which are present in most of the other species [6,12,24]. Thus, bostrychines are very significant chemotaxonomic characters allowing the discrimination of this species.…”

“…In general, the main problem in MAA analysis is the low retention of these metabolites on the column material, which results in low resolution and selectivity, especially when a large number of MAAs are analyzed. A prior study by some of the co-authors led to the method development and validation of an HPLC method that allowed the quantification of the 12 most common MAAs of Rhodophyta in 35 min using a YMC-Pack ODS column [12]. However, bostrychines of B. scorpioides extracts were not properly resolved with this method.…”

“…MAAs have been used in the past as biochemical indicators of taxonomy, e.g., for the discrimination of Grateloupia sp. of the Iberian Peninsula [25], for chemotaxonomic studies in the Prasiola-clade (Trebouxiophyceae, Chlorophyta) [26], or for the identification of cryptic species in the Bostrychia genus [11,12]. There are two proposed pathways for MAA biosynthesis, both identifying 4-deoxygadusol (4-DG) as the precursor of MAAs: the shikimate pathway and the pentose phosphate pathway [27].…”

“…According to several studies, the molecular diversity of Bostrychia species is greater than previously assumed, and this fact led to recircumscriptions of many species within the Bostrychieae [10]. It has been reported that some complexes include cryptic species and, in some cases, MAAs were used as chemotaxonomic markers for the identification of different chemotypes [11,12]. The unique bostrychines of B. scorpioides are completely absent in all other Bostrychia species and thus are very significant taxonomic characters.…”