Lipid Profiling Demonstrates That Suppressing Arabidopsis Phospholipase Dδ Retards ABA-Promoted Leaf Senescence by Attenuating Lipid Degradation

Abstract

Senescence is the last phase of the plant life cycle and has an important role in plant development. Degradation of membrane lipids is an essential process during leaf senescence. Several studies have reported fundamental changes in membrane lipids and phospholipase D (PLD) activity as leaves senesce. Suppression of phospholipase Dα1 (PLDα1) retards abscisic acid (ABA)-promoted senescence. However, given the absence of studies that have profiled changes in the compositions of membrane lipid molecules during leaf senescence, there is no direct evidence that PLD affects lipid composition during the process. Here, we show that application of n-butanol, an inhibitor of PLD, and N-Acylethanolamine (NAE) 12∶0, a specific inhibitor of PLDα1, retarded ABA-promoted senescence to different extents. Furthermore, phospholipase Dδ (PLDδ) was induced in leaves treated with ABA, and suppression of PLDδ retarded ABA-promoted senescence in Arabidopsis. Lipid profiling revealed that detachment-induced senescence had different effects on plastidic and extraplastidic lipids. The accelerated degradation of plastidic lipids during ABA-induced senescence in wild-type plants was attenuated in PLDδ-knockout (PLDδ-KO) plants. Dramatic increases in phosphatidic acid (PA) and decreases in phosphatidylcholine (PC) during ABA-induced senescence were also suppressed in PLDδ-KO plants. Our results suggest that PLDδ-mediated hydrolysis of PC to PA plays a positive role in ABA-promoted senescence. The attenuation of PA formation resulting from suppression of PLDδ blocks the degradation of membrane lipids, which retards ABA-promoted senescence.

Transcription Factor ATAF1 in Arabidopsis Promotes Senescence by Direct Regulation of Key Chloroplast Maintenance and Senescence Transcriptional Cascades

“…As shown here, the ataf1-4 mutant exhibits a delayed progression of senescence, while ATAF1 overexpressors exhibit precocious senescence in response to exogenously applied ABA. Additionally, the expression of PLDd, which is an important mediator in ABApromoted senescence (Jia et al, 2013), and genes involved in calcium signaling along with chlorophyll degradation is enhanced in ATAF1 overexpressors, highlighting the role of ATAF1 as a transcriptional regulator of ABA uptake and/or an amplifier of the signaling cascade that results in ABA-promoted senescence.…”

“…Recently, Jia et al (2013) reported that PHOSPHOLIPASE Dd (PLDd) plays an important role in ABA-promoted leaf senescence in Arabidopsis. The enzyme also functions in various environmental stresses, including the response to dehydration, salinity stress, and freezing, and plays a role in programmed cell death in response to H 2 O 2 treatment.…”

Phospholipase D δ knock-out mutants are tolerant to severe drought stress

“…8 Dehydration stimulates PA accumulation which is significantly suppressed in PLDd silenced and knock-out plants. 4.11,12 Jia and coworkers 34 showed that AtPLDd knockout plants display retarded ABA-induced senescence, by suppression of membrane lipid degradation. We showed that pldd plants have less ion leakage upon dehydration stress, and that the transient expression of AtPLDd in Nicotiana benthamiana provokes a wilting phenotype.…”

Molecular mechanisms for photosynthetic carbon partitioning into storage neutral lipids in Nannochloropsis oceanica under nitrogen-depletion conditions

“…6A). In higher plants, lipases can liberate fatty acids from membrane lipids for TAG biosynthesis [21,45,46]. Transcriptional expression of several lipase genes was significantly up-regulated in C. reinhardtii and N. oceanica under N depletion [24,34].…”