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

Abstract

Background Photosynthesis is a key process in plants that is compromised by the oxygenase activity of Rubisco, which leads to the production of toxic compound phosphoglycolate that is catabolized by photorespiratory pathway. Transformation of plants with photorespiratory bypasses have been shown to reduce photorespiration and enhance plant biomass. Interestingly, engineering of a single gene from such photorespiratory bypasses has also improved photosynthesis and plant productivity. Although single gene transformations may not completely reduce photorespiration, increases in plant biomass accumulation have still been observed indicating an alternative role in regulating different metabolic processes. Therefore, the current study was aimed at evaluating the underlying mechanism (s) associated with the effects of introducing a single cyanobacterial glycolate decarboxylation pathway gene on photosynthesis and plant performance. Methods Transgenic Arabidopsis thaliana plants (GD, HD, OX) expressing independently cyanobacterial decarboxylation pathway genes i.e., glycolate dehydrogenase, hydroxyacid dehydrogenase, and oxalate decarboxylase, respectively, were utilized. Photosynthetic, fluorescence related, and growth parameters were analyzed. Additionally, transcriptomic analysis of GD transgenic plants was also performed. Results The GD plants exhibited a significant increase (16%) in net photosynthesis rate while both HD and OX plants showed a non-significant (11%) increase as compared to wild type plants (WT). The stomatal conductance was significantly higher (24%) in GD and HD plants than the WT plants. The quantum efficiencies of photosystem II, carbon dioxide assimilation and the chlorophyll fluorescence-based photosynthetic electron transport rate were also higher than WT plants. The OX plants displayed significant reductions in the rate of photorespiration relative to gross photosynthesis and increase in the ratio of the photosynthetic electron flow attributable to carboxylation reactions over that attributable to oxygenation reactions. GD, HD and OX plants accumulated significantly higher biomass and seed weight. Soluble sugars were significantly increased in GD and HD plants, while the starch levels were higher in all transgenic plants. The transcriptomic analysis of GD plants revealed 650 up-regulated genes mainly related to photosynthesis, photorespiratory pathway, sucrose metabolism, chlorophyll biosynthesis and glutathione metabolism. Conclusion This study revealed the potential of introduced cyanobacterial pathway genes to enhance photosynthetic and growth-related parameters. The upregulation of genes related to different pathways provided evidence of the underlying mechanisms involved particularly in GD plants. However, transcriptomic profiling of HD and OX plants can further help to identify other potential mechanisms involved in improved plant productivity.

Identification of the Genes of the Plant Pathogen Pseudomonas syringae MB03 Required for the Nematicidal Activity Against Caenorhabditis elegans Through an Integrated Approach

“…The overall methodology for transcriptomics was followed as described previously ( Abbasi et al, 2021 ). Cellular RNA was isolated by Trizol method (Sigma-Aldrich, St. Louis, MO, United States).…”

Here comes the sun: How optimization of photosynthetic light reactions can boost crop yields

“…In recent years, different strategies to improve crop yields have been proposed and reviewed, such as: (i) introducing photorespiratory bypasses (Betti et al, 2016; Hagemann and Bauwe, 2016; South et al, 2018; Eisenhut et al, 2019; López‐Calcagno et al, 2019; Maurino, 2019; Shen et al, 2019; Khurshid et al, 2020; Wang et al, 2020; Abbasi et al, 2021); (ii) introducing algal/cyanobacterial carbon concentrating mechanisms (McGrath and Long, 2014; Rae et al, 2017; Long et al, 2018; Atkinson et al, 2020; Hennacy and Jonikas, 2020; Chen et al, 2021; Rottet et al, 2021); (iii) introducing the C4 photosynthesis pathway into C3 plants (Ermakova et al, 2020, 2021a); (iv) improving mesophyll conductance (Hanba et al, 2004; Xu et al, 2019; Lundgren and Fleming, 2020; Ermakova et al, 2021c); (v) modifying metabolic processes (Rossi et al, 2015; South et al, 2019); and (vi) modifying circadian rhythms and introducing chronocultures (Steed et al, 2021). During the second half of the 20th century, the Green Revolution led to improved grain yields through conventional breeding techniques and improved pest/disease control.…”

Transcriptome and association mapping revealed functional genes respond to drought stress in Populus

“…Different genotypic combinations of PtoeIF-2B, PtoABF3 had distinct contributions to the expression levels of PtoHDA15 and PtoVHA-c expression (Figure 4; Supplementary Table S14). Indeed, eIF-2B and Lhca4 were down-regulated under drought stress in a drought sensitive wheat cultivar (Abbasi et al, 2021). These findings improve our understanding of the role of epistasis in drought stress adaptation in trees (Du et al, 2019).…”