Role ofArabidopsisAtPI4Kγ3, a typeIIphosphoinositide 4‐kinase, in abiotic stress responses and floral transition

Abstract

SummaryPhosphoinositides (PIs) are essential metabolites which are generated by various lipid kinases and rapidly respond to a variety of environmental stimuli in eukaryotes. One of the precursors of important regulatory PIs, phosphatidylinositol (PtdIn) 4-phosphate, is synthesized by PtdIns 4-kinases (PI4K). Despite its wide distribution in eukaryotes, its role in plants remains largely unknown. Here, we show that the activity of AtPI4Kc3 gene, an Arabidopsis (Arabidopsis thaliana) type II PtdIn 4-kinase, is regulated by DNA demethylation and some abiotic stresses. AtPI4Kc3 is targeted to the nucleus and selectively bounds to a few PtdIns. It possessed autophosphorylation activity but unexpectedly had no detectable lipid kinase activity. Overexpression of AtPI4Kc3 revealed enhanced tolerance to high salinity or ABA along with inducible expression of a host of stress-responsive genes and an optimal accumulation of reactive oxygen species. Furthermore, overexpressed AtPI4Kc3 augmented the salt tolerance of bzip60 mutants. The ubiquitin-like domain of AtPI4Kc3 is demonstrated to be essential for salt stress tolerance. Besides, AtPI4Kc3-overexpressed plants showed a late-flowering phenotype, which was caused by the regulation of some flowering pathway integrators. In all, our results indicate that AtPI4Kc3 is necessary for reinforcement of plant response to abiotic stresses and delay of the floral transition.

LPIAT, a lyso-Phosphatidylinositol Acyltransferase, Modulates Seed Germination in Arabidopsis thaliana through PIP Signalling Pathways and is Involved in Hyperosmotic Response

“…On the contrary, when the orthologue gene (udbkγ7) is disrupted in Arabidopsis, the sensitivity to salt and ABA increased [10]. These results have also been observed when another PI4Kinase was unexpressed [46]. These phenotypes are in agreement with this study if we assumed that the PI species remodelled through LPIAT are preferentially phosphorylated by a PI kinase during seed imbibition.…”

“…As the aleurone-like cell layer is known to be involved in the control of seed dormancy and germination, especially by synthesizing and releasing ABA towards the embryo, that blocks the germination [44,45], we studied seed germination in function of the expression level of LPIAT. Moreover, since phosphoinositides mediated plant-response against stress [46], the development of young seedlings throughout drought and osmotic stresses was also investigated.…”

Nicotiana benthamiana phosphatidylinositol 4‐kinase type II regulates chilli leaf curl virus pathogenesis

“…HCV hijacks PI4KIIIα in order to create its own replication niche and this is achieved as PI4KIIIα produces PI4P at the site of replication, forming a membranous web and the replicating virus is thus shielded from the host defence machinery (Berger et al ., , ). Recently, the role of type II PI4Kγ3 in abiotic stress response and floral transition in plants has been demonstrated (Akhter et al ., ) while another type II PI4K (γ5) interacts with membrane target transcription factor ANAC078 to regulate auxin biosynthesis and leaf margin development (Tang et al ., ). However, the role of PI4Ks in plant virus bi‐fluorescence complementation assay pathogenesis is not yet known.…”

The Transcriptional Modulation of Inositols and Raffinose Family Oligosaccharides Pathways in Plants — An (A)Biotic Stress Perspective

“…From the wide spectrum of analyzed genes, a range of effects on plants at different levels was observed. These effects have shown associations with hormone signaling pathways, such as ABA [12], influences in photosystems [21,22], with reactive oxygen species (ROS; [23]), with relative water content, with osmotic adjustment [24], among others (Table 1).…”