An engineered lipid remodeling system using a galactolipid synthase promoter during phosphate starvation enhances oil accumulation in plants

Abstract

Inorganic phosphate (Pi) depletion is a serious problem for plant growth. Membrane lipid remodeling is a defense mechanism that plants use to survive Pi-depleted conditions. During Pi starvation, phospholipids are degraded to supply Pi for other essential biological processes, whereas galactolipid synthesis in plastids is up-regulated via the transcriptional activation of monogalactosyldiacylglycerol synthase 3 (MGD3). Thus, the produced galactolipids are transferred to extraplastidial membranes to substitute for phospholipids. We found that, Pi starvation induced oil accumulation in the vegetative tissues of various seed plants without activating the transcription of enzymes involved in the later steps of triacylglycerol (TAG) biosynthesis. Moreover, the Arabidopsis starchless phosphoglucomutase mutant, pgm-1, accumulated higher TAG levels than did wild-type plants under Pi-depleted conditions. We generated transgenic plants that expressed a key gene involved in TAG synthesis using the Pi deficiency–responsive MGD3 promoter in wild-type and pgm-1 backgrounds. During Pi starvation, the transgenic plants accumulated higher TAG amounts compared with the non-transgenic plants, suggesting that the Pi deficiency–responsive promoter of galactolipid synthase in plastids may be useful for producing transgenic plants that accumulate more oil under Pi-depleted conditions.

Silicon Compensates Phosphorus Deficit-Induced Growth Inhibition by Improving Photosynthetic Capacity, Antioxidant Potential, and Nutrient Homeostasis in Tomato

“…In the present study, LP stress decreased net photosynthetic rate, which was attributed to reduced stomatal conductance in tomato leaves (Table 2). Notably, P deficit conditions lead to breakdown of phospholipids in the chloroplast membranes to release Pi, which could be a potential reason for reduced photosynthetic rate [42]. In addition, enhanced carbohydrate (starch and sugars) accumulation in chloroplasts under Pi-depleted conditions may also result in attenuated photosynthetic activity [42,43].…”

“…Notably, P deficit conditions lead to breakdown of phospholipids in the chloroplast membranes to release Pi, which could be a potential reason for reduced photosynthetic rate [42]. In addition, enhanced carbohydrate (starch and sugars) accumulation in chloroplasts under Pi-depleted conditions may also result in attenuated photosynthetic activity [42,43]. However, exogenous Si application significantly increased photosynthetic pigment contents as well as net photosynthetic rate under LP stress compared with that under LP stress alone.…”

Lipid Trafficking at Membrane Contact Sites During Plant Development and Stress Response

“…Lipid droplets have a well-known function in energy storage but proteomic analyses of plant LDs showed that they might also play alternative roles, particularly during stress (Pyc et al, 2017; Yang and Benning, 2018). TAG accumulation was observed during nitrogen or Pi deprivation in higher plants (Gaude et al, 2007; Pant et al, 2015; Shimojima et al, 2015; Mei et al, 2017), and such increases were also significantly enhanced in the presence of sugar (Yang et al, 2011). In A. thaliana cell cultures, TAG accumulation seems to be a frequent response to cell growth arrest mediated by nutrient stresses or chemical drugs, such as MTX (Mei et al, 2017).…”

C1 Metabolism Inhibition and Nitrogen Deprivation Trigger Triacylglycerol Accumulation in Arabidopsis thaliana Cell Cultures and Highlight a Role of NPC in Phosphatidylcholine-to-Triacylglycerol Pathway

“…These observations are at the basis of numerous strategies to produce third generation biofuels. These effects have been less studied in higher plants, but it was observed in Arabidopsis seedlings that the amount of TAG increased during nitrogen deprivation (Gaude et al, 2007; Shimojima et al, 2015), and that such increase was also significantly enhanced in the presence of sugar (Yang et al, 2011). The reasons why nutrient deficiencies induce TAG accumulation are not clear.…”