Expression of Genes Related to Carrageenan Synthesis during Carposporogenesis of the Red Seaweed Grateloupia imbricata

Abstract

Carrageenan, the foremost constituent of extracellular matrix of some rhodophyta, is a galactan backbone with a different number of sulphate groups attached. Variations of degree of sulphation are associated with different types of carrageenans, which vary according to seaweed life cycles, and have consequences for the exploitation of this raw material. In this work, we used three well-recognised stages of development thalli and two stages of cystocarp maturation to analyse genes that encode addition and elimination of sulphate groups to cell-wall galactan of the red seaweed Grateloupia imbricata. Expressions of carbohydrate sulfotransferase and galactose-6 sulfurylase and genes encoding stress proteins such as cytochrome P450 and WD40, were examined. Results showed that transcript expression of carbohydrate sulfotransferase occurs at all stage of thalli development. Meanwhile galactose-6 sulfurylase expressions displayed different roles, which could be related to a temporal regulation of cystocarp maturation. Cytochrome P450 and WD40 are related to the disclosure and maturation of cystocarps of G. imbricata. Our conclusion is that differential expression of genes encoding proteins involved in the sulphation and desulphation of galactan backbone is associated with alterations in thalli development and cystocarp maturation in the red seaweed Grateloupia imbricata. Exploitation of industry-valued carrageenan will depend on insight into gene mechanisms of red seaweeds.

S-Assimilation Influences in Carrageenan Biosynthesis Genes during Ethylene-Induced Carposporogenesis in Red Seaweed Grateloupia imbricata

“…According to sulfation degrees, different types of carrageenans can be synthetized, which then shape gel networks. Moreover, the sulfation and desulfation degree of galactan backbone of SG is associated with alterations in thalli development and cystocarp maturation in red seaweeds [5]. Given that carposporogenesis in G. imbricata is an asynchronous process, in which the developmental stage of cystocarps is difficult to determine accurately, the pursuit of the ODC gene confirmed a down expression as development and maturation of reproductive structures (cystocarps) 2) at day 3(addition of S-source) and day 10 (S-source plus fluxed ethylene) in thalli of Grateloupia imbricata (as in experiment A in Figure 2).…”

“…Moreover, it can be assumed that ST gene expressions, which encode proteins in charge of adding sulfate groups to cell-wall galactan, might be a consequence of carrageenan synthesis and also neutral polysaccharides, which are a constituent of mucilage in red algae [ 38 ]. No changes in ST expression were observed in G. imbricata when through field sampling; ST1 and ST2 were also unaltered in infertile, fertilized (well-developed cystocarps), and fertile (fully developed cystocarps) thalli [ 5 ].…”

“…Carrageenan type and the degree of sulfation render the thallus flexible, and differences in the strengths of carrageenans are related to algal development stage. Genes encoding carbohydrate sulfotransferase and galactose-6sulfurylase have been associated at different development stages of red seaweed Grateloupia imbricata with the seasonal period [5]. Synthesis of cell-wall-sulfated galactans proceeds through UDP galactose, a major nucleotide sugar in red seaweed [6].…”

The antiviral activity of iota-, kappa-, and lambda-carrageenan against COVID-19: A critical review

“…33 The galactan backbone of the polymer is synthesized in the Golgi bodies of the cell, while the sulfation step occurs in the cell wall via a sulfotransferase pathway. 33 , 34 , 35 Carrageenan bioactives are polydisperse and have a wide range of molecular weights. It is primarily found in the Gigartinaceae and Solieriaceae families, 36 , 37 as well as the Furcellariaceae , Solieriaceae, Phyllophoraceae , and Hypneaceae families.…”

Advances in Research on Antiviral Activities of Sulfated Polysaccharides from Seaweeds

“…Carrageenan is a soluble sulfated galactan isolated from red seaweed where it is a component of the outer cell wall and intracellular matrix, and it accounts for 30–70% of the dry weight of red algae. The galactan backbone is produced in the Golgi apparatus and is subsequently sulfated by sulfotransferases in the cell wall [ 37 ]. Commercially, red seaweed is considered more valuable than brown and green algae.…”