Phosphoglycerolipids are master players in plant hormone signal transduction

Abstract

Phosphoglycerolipids are essential structural constituents of membranes and some also have important cell signalling roles. In this review, we focus on phosphoglycerolipids that are mediators in hormone signal transduction in plants. We first describe the structures of the main signalling phosphoglycerolipids and the metabolic pathways that generate them, namely the phospholipase and lipid kinase pathways. In silico analysis of Arabidopsis transcriptome data provides evidence that the genes encoding the enzymes of these pathways are transcriptionally regulated in responses to hormones, suggesting some link with hormone signal transduction. The involvement of phosphoglycerolipid signalling in the early responses to abscisic acid, salicylic acid and auxins is then detailed. One of the most important signalling lipids in plants is phosphatidic acid. It can activate or inactivate protein kinases and/or protein phosphatases involved in hormone signalling. It can also activate NADPH oxidase leading to the production of reactive oxygen species. We will interrogate the mechanisms that allow the activation/deactivation of the lipid pathways, in particular the roles of G proteins and calcium. Mediating lipids thus appear as master players of cell signalling, modulating, if not controlling, major transducing steps of hormone signals.

The Arabidopsispi4kIIIβ1β2double mutant is salicylic acid-overaccumulating: a new example of salicylic acid influence on plant stature

“…Lipid signaling is a main constituent of hormonal regulation. 17 We showed that SA activates PI4K and phospholipase D. [18][19][20] It is not impossible that such activity might participate in counteracting the effects of the soconsidered developmental hormones. It is at least worth investigating this hypothesis.…”

“…Interestingly, phosphoinositide gradients were shown to be necessary for a correct polarity of PIN auxin carriers. 17,23,24 Therefore, the double mutation could lead to an alteration in phosphoinositide gradient formation, thus leading to deficient root tip growth.…”

Comparative Genomic View of The Inositol-1,4,5-Trisphosphate Receptor in Plants

“…These second messengers then activate protein kinase C (PKC) and the ER-localised IP 3 receptor, respectively, in animal cells [1,2]. However, although the PI-PLC signaling cascade is present in plants [5][6][7], genes encoding PKC and the IP 3 receptor have not been found in terrestrial plant genomes, suggesting differences in second messenger systems between animals and plants. To date, the genomes of a variety of unicellular and multicellular algae have been sequenced [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] as shown in (Table 1).…”

“…They have also proposed a parallel between the IP 3 and IP 6 signalling systems because these two molecules are both produced by the action of PI-PLC. Although neither an IP 3 nor an IP 6 receptor have yet been identified in terrestrial plants, it is possible that an IP 3 receptor or an IP 6 receptor of unknown structure is present in streptophytes. Taken together, comparative genomic information clearly demonstrates the loss of the IP 3 receptor gene in red algae, green algae except for Volvocales and streptophytes during plant evolution.…”

“…However, IP 3 -dependent transient Ca 2+ release from intracellular stores has been shown in these organisms by physiological experiments, although whether plants lacking the IP 3 receptor might both possess a common system for such transient Ca 2+ release is uncertain. Therefore, the identification and characterization of genes encoding putative IP 3 or IP 6 receptors of unknown structure is of the highest priority for elucidating and comparing the regulation of the PI-PLC signalling cascade between IP 3 receptor-carrying and -lacking algae. Ostreococcus lucimarinus [9] Chlorophyceae Volvocales Chlamydomonadaceae Chlamydomonas reinhardtii [10] Volvocaceae Volvox carteri [11] Chlorococcales Coccomyxaceae Coccomyxa subellipsoidea [12] Rhodophyta Cyanidiophyceae Cyanidiales Cyanidiaceae Cyanidioschyzon merolae [13] Galdieria sulphuraria [14] Porphyridiophyceae Porphyridiales Porphyridiaceae Porphyridium purpureum [15] Rhodophyceae Bangiales Bangiaceae Pyropia yezoensis [16] Florideophyceae Gigartinales Gigartinaceae Chondrus crispus [17] Glaucophyta Glaucophyceae Glaucocystales Glaucocystaceae Cyanophora paradoxa [18] Heterokontophyta Coscinodiscophyceae Thalassiosirales Thalassiosiraceae Thalassiosira pseudonana [19] Bacillariophyceae Naviculales Phaeodactylaceae Phaeodactylum tricornutum [20] Pelagophyceae …”