DIACYLGLYCEROL KINASE 5 participates in flagellin-induced signaling in Arabidopsis

Abstract

Flagellin perception is a keystone of pattern-triggered immunity in plants. The recognition of this protein by a plasma membrane receptor complex is the beginning of a signaling cascade that includes protein phosphorylation and the production of reactive oxygen species (ROS). In both Arabidopsis (Arabidopsis thaliana) seedlings and suspension cells, we found that treatment with flg22, a peptide corresponding to the most conserved domain of bacterial flagellin, caused a rapid and transient decrease in the level of phosphatidylinositol 4,5-bisphosphate along with a parallel increase in phosphatidic acid (PA). In suspension cells, inhibitors of either phosphoinositide-dependent phospholipases C (PLC) or diacylglycerol kinases (DGKs) inhibited flg22-triggered PA production and the oxidative burst. In response to flg22, receptor-like kinase-deficient fls2, bak1 and bik1 mutants (FLAGELLIN SENSITIVE 2, BRASSINOSTEROID INSENSITIVE 1–associated kinase 1 and BOTRYTIS-INDUCED KINASE 1, respectively) produced less PA than wild-type (WT) plants, whereas this response did not differ in NADPH oxidase-deficient rbohD (RESPIRATORY BURST OXIDASE HOMOLOG D) plants. Among the DGK-deficient lines tested, the dgk5.1 mutant produced less PA and less ROS after flg22 treatment compared to WT seedlings. In response to flg22, dgk5.1 plants showed lower callose accumulation and impaired resistance to Pseudomonas syringae pv. tomato DC3000 hrcC-. Transcriptomics revealed that the basal expression of defense-related genes was altered in dgk5.1 seedlings compared to the WT. A GFP-DGK5 fusion protein localized to the plasma membrane, where RBOHD and PLC2 (proteins involved in plant immunity) are also located. The role of DGK5 and its enzymatic activity in flagellin signaling and fine-tuning of early immune responses in plant-microbe interactions is discussed.

Comprehensive analysis of glycerolipid dynamics during tobacco pollen germination and pollen tube growth

“…Several, not mutually exclusive, explanations for this discrepancy can be drawn. First, both approaches tackle the lipid quantification from a slightly different angle: while lipidomics gathers steady-state levels of the lipids with great accuracy and distinguishes individual lipid species, in situ lipase analysis (or any other lipid pulse-labeling technique) uncovers immediate dynamical changes and fluxes ( Kalachova et al., 2022 ). Second, the lipase activity analyses visualize specific enzyme activities, while the lipidomic approaches do not discriminate.…”

“…Molecular cloning of the construct for genetically-encoded PA sensor (pUBQ::mCherry-NES-2xSpo20-PABD) was described previously ( Kalachova et al., 2022 ). The final construct was transferred into Agrobacterium tumefaciens strain GV3101, which was used to transform tobacco ( N. tabacum L. cv.…”

A frosty genetic screen unmasks a major regulatory role for SHORT VEGETATIVE PHASE of flowering in response to a cold snap

“…DGK5 catalyzes the conversion of diacylglycerol to phosphatidic acid. Loss-of-function mutants have impaired resistance to pathogens and decreased freezing tolerance (Tan et al, 2018; Kalachova et al, 2022). However, no effect on flowering has been reported.…”

Date palm acclimates to aridity by diverting organic osmolytes for root osmotic adjustment in parallel with leaf membrane remodeling and ROS scavenging

“…S1c). Both are involved in the Kennedy pathway, where phosphocholine phosphatase hydrolyzes phosphorylated head groups of phosphocholine (Tannert et al, 2021) (Kalachova et al 2022) such as drought (Mane et al, 2007). Related to TAG synthesis, transcripts of three homologs of acyl-CoA:diacylglycerol acyltransferase (DGAT1,2) were 2-fold LOG2 up-regulated after 31 days of drought exposure.…”