Glycerol‐3‐phosphate metabolism plays a role in stress response in the red alga Pyropia haitanensis

Abstract

Glycerol-3-phosphate (G3P) has been suggested as a novel regulator of plant defense signaling, however, its role in algal resistance remains largely unknown. The glycerol kinase (also designated as NHO1) and NAD-dependent G3P dehydrogenase (GPDH) are two key enzymes involved in the G3P biosynthesis. In our study, we cloned the full-length cDNA of NHO1 (NHO1Ph ) and GPDH (GPDHP h ) from the red alga Pyropia haitanensis (denoted as NHO1Ph and GPDHP h ) and examined their expression level under flagellin peptide 22 (flg22) stimulation or heat stress. We also measured the level of G3P and floridoside (a downstream product of G3P in P. haitanensis) under flg22 stimulation or heat stress. Both NHO1Ph and GPDHP h shared high sequence identity and structural conservation with their orthologs from different species, especially from red algae. Phylogenetic analysis showed that NHO1s and GPDHs from red algae were closely related to those from animals. Under flg22 stimulation or heat stress, the expression levels of NHO1Ph and GPDHP h were up-regulated, G3P levels increased, and the contents of floridoside decreased. But the floridoside level increased in the recovery period after heat stress. Taken together, we found that G3P metabolism was associated with the flg22-induced defense response and heat stress response in P. haitanensis, indicating the general conservation of defense response in angiosperms and algae. Furthermore, floridoside might also participate in the stress resistance of P. haitanensis.

Putative trehalose biosynthesis proteins function as differential floridoside-6-phosphate synthases to participate in the abiotic stress response in the red alga Pyropia haitanensis

“…In particular, the levels of PhTPS1 and PhTPS4 were up-regulated most significantly, indicating that floridoside and isofloridoside may all be involved in the response to desiccation, with floridoside acting as an osmolyte, whereas the function of isofloridoside is unknown.Marine algae are subjected to high temperature stress. Under this stress, the defense system is activated[15]. We previously found that the content of floridoside decreased slightly under high temperature, but increased significantly during the recovery process.…”

“…Curiously, no FPS enzymatic activity was indicated for the PhTPS2 protein. Although PhTPS4 has FPS enzymatic activity, it is located near the Class II proteins.Apart from its role in organic carbon transport and/or as a short-term reservoir recycled to provide organic carbon for cellular needs, the accumulation of floridoside has been associated with improved stress tolerance toward abiotic stress[15]. As the major organic osmolyte in red algae, floridoside isused as an osmoprotectant.…”

Putative trehalose biosynthesis proteins function as differential floridoside-6-phosphate synthases to participate in the abiotic stress response in the red alga Pyropia haitanensis

“…Apart from its role in organic carbon transport and/or as a short-term reservoir recycled to provide organic carbon for cellular needs, the accumulation of floridoside has been associated with improved stress tolerance toward abiotic stress [15]. As the major organic osmolyte in red algae, floridoside is used as an osmoprotectant.…”

“…Marine algae are subjected to high temperature stress. Under this stress, the defense system is activated [15]. We previously found that the content of floridoside decreased slightly under high temperature, but increased significantly during the recovery process.…”

“…In previous research on Pyropia haitanensis , and we found that the contents of floridoside and isofloridoside varied markedly under desiccation and high temperature stress [15]. However, the genes encoding (iso)floridoside biosynthetic enzymes remain unknown.…”