Phytohormones in red seaweeds: a technical review of methods for analysis and a consideration of genomic data

Abstract

Emerging studies suggest that seaweeds contain phytohormones; however, their chemical entities, biosynthetic pathways, signal transduction mechanisms, and physiological roles are poorly understood. Until recently, it was difficult to conduct comprehensive analysis of phytohormones in seaweeds because of the interfering effects of cellular constituents on fine quantification. In this review, we discuss the details of the latest method allowing simultaneous profiling of multiple phytohormones in red seaweeds, while avoiding the effects of cellular factors. Recent studies have confirmed the presence of indole-3-acetic acid (IAA), N 6 -(Δ2-isopentenyl)adenine (iP), (+)-abscisic acid (ABA), and salicylic acid, but not of gibberellins and jasmonate, in Pyropia yezoensis and Bangia fuscopurpurea. In addition, an in silico genome-wide homology search indicated that red seaweeds synthesize iP and ABA via pathways similar to those in terrestrial plants, although genes homologous to those involved in IAA biosynthesis in terrestrial plants were not found, suggesting the epiphytic origin of IAA. It is noteworthy that these seaweeds also lack homologues of known factors involved in the perception and signal transduction of IAA, iP, and ABA. Thus, the modes of action of these phytohormones in red seaweeds are unexpectedly dissimilar to those in terrestrial plants.

Origin and evolution of gibberellin signaling and metabolism in plants

“…This is the case of Gibberella fujikuroi KAO, that produces GA 14 from ent-kaurenoic acid instead of GA 12 [104]. On the other hand, the algal groups Chlorophyta, Charophyta, and Phaeophyceae, have been reported to produce bioactive GAs in more than 30 species [106-108], while none has been found in Rhodophyta species [109]. Given that Chlorophyta and Charophyta lack clear CPS and KS orthologs [79], and Phaeophyceae algae are distantly related to Archaeplastid lineages [110], the most plausible explanation is that so far unidentified pathways for GA biosynthesis may have evolved independently in multiple lineages, in an extreme case of convergent evolution between kingdoms and domains.…”

Seaweed reproductive biology: environmental and genetic controls

“…In addition, whether the phytohormones of land plants are shared with algae is controversial, especially given the distinct evolutionary relationship. Many of the signaling pathway components are not present in basal early-diverging lineages of the Streptophyta and/or other algal lineages (De Smet et al 2010, Lu andMori et al 2017) making it less likely that a phytohormone function could have been inherited from a common unicellular ancestor. Nonetheless, evidence for phytohormone function in unicellular algae is beginning to accumulate, such as the role of abscisic acid and auxins in regulation of growth in unicellular green algae and diatoms ( Kobayashi et al 1997, Yoshida et al 2004, Park et al 2013, Lu et al 2014, Amin et al 2015.…”

“…Interactions have also been observed in land plants where pathogenic or symbiotic bacteria can influence the growth of a plant by manipulating its auxin homeostasis (Lambrecht et al 2000, Frugier et al 2008, Ludwig-Müller 2015. Therefore it is not certain if phytohormones are synthesized by algae themselves and metabolic auxotrophy may have evolved as a result of mutualism with microorganisms due to the aquatic environment (Kazamia et al 2016, Mori et al 2017.…”

Identification and Quantification of Plant Growth Regulators and Antioxidant Compounds in Aqueous Extracts of Padina durvillaei and Ulva lactuca

“…The presence and number of PGRs in algae and terrestrial plants differ according to the species or variety [12,22]. For example, Mori et al [41] reported the identification of auxins, cytokinins, and salicylic acid (SA), but not AG3 and jasmonates, in extracts of two red algae (Pyropia yezoensis and Bangia fuscopurpurea). Another study involving fourteen seaweeds in the Turkey coast reported the presence of five PGRs (t-zeatine (t-Z), IAA, GA3, ABA, and 6-benzyl amino purine (BAP) in two algae, namely Petalonia fascia (brown algae) and Caulerpa racemosa var.…”