The Pyruvate-Phosphate Dikinase (C4-SmPPDK) Gene From Suaeda monoica Enhances Photosynthesis, Carbon Assimilation, and Abiotic Stress Tolerance in a C3 Plant Under Elevated CO2 Conditions

Abstract

A pyruvate-phosphate dikinase (C 4 -PPDK) gene was cloned from Suaeda monoica, which had a single-cell C 4 photosynthesis pathway without Kranz anatomy and was functionally validated in a C 3 model plant under different abiotic stress conditions in an ambient and elevated CO 2 environment. Overexpression of SmPPDK promoted growth of C 3 transgenic plants, enhancing their photosynthesis (CO 2 assimilation) by lowering photorespiration under stress conditions. Transgenic plants also showed an improved physiological status, with higher relative water content (RWC), membrane integrity, concentration of glycine betaine, total soluble sugars, free amino acids, polyphenols and antioxidant activity, and lower electrolyte leakage, lipid peroxidation, free radical accumulation, and generation of reactive oxygen species (ROS), compared to control plants. Moreover, SmPPDK transgenic plants exhibited earlier flowering and higher dry biomass compared to controls. These results suggested that the C 4 -PPDK gene was appropriate for improvement of carbon assimilation, and it also played an important role in adaption to salinity and severe drought-induced stress. More intriguingly, an elevated CO 2 environment alleviated the adverse effects of abiotic stress, particularly caused by drought through coordination of osmoprotectants and antioxidant defense systems. The molecular, physiological, metabolic, and biochemical indicators ameliorated the overall performance of model C 3 plants overexpressing the C 4 -PPDK gene in an elevated CO 2 environment, by lowering photorespiration metabolic processes, however, further studies are needed to confirm its precise role in C 3 plants as protection against future climate change.

Introgression of a novel cold and drought regulatory‐protein encoding CORA‐like gene, SbCDR, induced osmotic tolerance in transgenic tobacco

“…Modulation in the overall metabolome due to the developmental and environmental cues has previously been reported (Patel et al, 2020; Shekhar, Agrawal, et al, 2016). Even an overall reprogramming of the accumulation of primary and secondary metabolites due to the ectopic expression of a single gene has also been studied (Shekhar et al, 2016b; Yadav et al, 2020). The plant accumulates several organic acids, amino acids, polyamines and lipids, besides producing different metabolites in response to stress conditions (Guy et al, 2008; Sharma et al, 2021).…”

“…Total metabolites were extracted from selected transgenic and WT plants, and analysed by gas chromatography–mass spectrometry (Yadav et al, 2020). Briefly, fine powder of leaf samples (1 g) were made using liquid N 2 , and total metabolites were extracted with 100% ethanol (ice‐cold).…”

Expression of cyanobacterial genes enhanced CO2 assimilation and biomass production in transgenic Arabidopsis thaliana

“…Engineering of photorespiratory bypasses, complete as well as partial, and modifications in other genes, such as phosphophenol pyruvate carboxylase (PEPC), cytochrome c 6 (Cyt c 6 ), and pyruvate phosphate dikinase (PPDK) have resulted in improved photosynthesis, as well as an enhancement in soluble sugars and starch ( Kebeish et al, 2007 ; Xia & Cao, 2013 ; Nölke et al, 2014 ; Dalal et al, 2015 ; Yadav et al, 2018 ; Yadav, Rathore & Mishra, 2020 ). Nölke et al (2014) have also reported an enhancement in sugar contents by transforming GDH alone in potato.…”

Introgression of SbERD4 Gene Encodes an Early-Responsive Dehydration-Stress Protein That Confers Tolerance against Different Types of Abiotic Stresses in Transgenic Tobacco

“…Commonly, plants modulate their several metabolic and physiological processes to cope with these conditions. Indeed, many stress-related genes were characterized from halophytes, and novel candidate genes are always welcomed, which provide endurance for a sustainable demand of agriculture [ 8 , 11 , 42 ]. In this study, a novel CSC1-like gene SbERD4 was isolated from a nutritionally and industrially important extreme halophyte Salicornia brachiata [ 43 , 44 , 45 , 46 ], and it was functionally characterized into Nicotiana tabacum cv.…”