Arabidopsis Phosphatidic Acid Phosphohydrolases Are Essential for Growth under Nitrogen-Depleted Conditions

Abstract

The Arabidopsis homologs of mammalian lipin, PAH1 and PAH2, are cytosolic phosphatidic acid phosphohydrolases that are involved in phospholipid biosynthesis and are essential for growth under phosphate starvation. Here, pah1 pah2 double-knockout mutants were found to be hypersensitive to nitrogen (N) starvation, whereas transgenic plants overexpressing PAH1 or PAH2 in the pah1 pah2 mutant background showed a similar growth phenotype as compared with wild type (WT) under N starvation. The chlorophyll content of pah1 pah2 was significantly lower than that of WT, whereas the chlorophyll content and photosynthetic activity of the transgenic plants were significantly higher than those of WT under N-depleted conditions. Membrane glycerolipid composition of the pah1 pah2 mutants showed a significant decrease in the mole percent of chloroplast lipids to other phospholipids, whereas membrane lipid composition did not differ between transgenic plants and WT plants. Pulse-chase labeling experiments using plants grown under N-depleted conditions showed that, in pah1 pah2 plants, the labeling percent of chloroplast lipids such as phosphatidylglycerol and monogalactosyldiacylglycerol in the total glycerolipids was significantly lower than in WT. Moreover, N starvation-induced degradation of chloroplast structure was enhanced in pah1 pah2 mutants, and the membrane structure was recovered by complementation with PAH1. Thus, PAH is involved in maintaining chloroplast membrane structure and is required for growth under N-depleted conditions.

RNA-seq profiling in leaf tissues of two soybean (Glycine max [L.] Merr.) cultivars that show contrasting responses to drought stress during early developmental stages

“…Many of our DEGs were involved in glycerolipid metabolism and acted in glycerolipid biosynthesis, remodeling, or degradation pathways. For example, several acyltransferases, including GPAT2, GPAT3, and LPAT5, are reported to be responsible for glycerophospholipid biosynthesis in Arabidopsis (D’Auria 2006 ); CCT and CKs regulate levels of PC, a glycerophospholipid substrate (Craddock et al 2015 ; Lin et al 2019 ); GDPD and several alpha/beta-hydrolases are responsible for glycerophospholipid degradation; DGK10, PAH1, and DGAT1 are involved in diacylglycerol metabolism, which is involved in signaling under stressful conditions (Yoshitake et al 2017 ; Tan et al 2018 ) (Table 1 ). These DEGs may function in responding to stress through regulating lipid signaling pathways.…”

Longer Duration of Active Oil Biosynthesis during Seed Development Is Crucial for High Oil Yield—Lessons from Genome-Wide In Silico Mining and RNA-Seq Validation in Sesame

“…A double mutant of the two At PAH genes ( At PAH1 and 2) is affected in phosphatidylcholine production at the ER [ 113 ]. These two proteins have been reported as being involved in phospholipid homeostasis in the ER and in TAG synthesis, especially under N starvation [ 115 ].…”

Autophagy triggered by iron‐mediated ER stress is an important stress response to the early phase of Pi starvation in plants

“…Total lipids were extracted from seedlings using the method of Bligh & Dyer (1959). Polar membrane lipids were separated by two‐dimensional thin‐layer chromatography (Yoshitake et al., 2017). After lipids were stained with 0.01% (w/v) primulin in 80% (v/v) acetone, the silica gel in each stained area was scraped off and accumulated.…”