Overexpression of an Agave Phosphoenolpyruvate Carboxylase Improves Plant Growth and Stress Tolerance

Abstract

It has been challenging to simultaneously improve photosynthesis and stress tolerance in plants. Crassulacean acid metabolism (CAM) is a CO2-concentrating mechanism that facilitates plant adaptation to water-limited environments. We hypothesized that the ectopic expression of a CAM-specific phosphoenolpyruvate carboxylase (PEPC), an enzyme that catalyzes primary CO2 fixation in CAM plants, would enhance both photosynthesis and abiotic stress tolerance. To test this hypothesis, we engineered a CAM-specific PEPC gene (named AaPEPC1) from Agave americana into tobacco. In comparison with wild-type and empty vector controls, transgenic tobacco plants constitutively expressing AaPEPC1 showed a higher photosynthetic rate and biomass production under normal conditions, along with significant carbon metabolism changes in malate accumulation, the carbon isotope ratio δ13C, and the expression of multiple orthologs of CAM-related genes. Furthermore, AaPEPC1 overexpression enhanced proline biosynthesis, and improved salt and drought tolerance in the transgenic plants. Under salt and drought stress conditions, the dry weight of transgenic tobacco plants overexpressing AaPEPC1 was increased by up to 81.8% and 37.2%, respectively, in comparison with wild-type plants. Our findings open a new door to the simultaneous improvement of photosynthesis and stress tolerance in plants.

CAM photosynthesis: the acid test

“…Evidence of a tight interconnection between the circadian oscillator and dark CO 2 fixation is also shown by the observation that suppression of PEPC expression by RNA interference results in altered expression of certain core circadian clock genes (Boxall et al ., 2020 ). On the other hand, overexpression of the CAM isoform of PEPC in a C 3 background ( Arabidopsis or tobacco), while leading to increased malate content and daytime accumulation, does not itself result in a switch to night‐time acidification (Lim et al ., 2019 ; Liu et al ., 2021 ).…”

Crataegus oxyacantha Extract as a Biostimulant to Enhance Tolerance to Salinity in Tomato Plants

“…Liu et al (2021) [ 42 ] demonstrated that the overexpression of PEPc activity significantly increases salt tolerance in transgenic tobacco plants. In general, this enhancement is related to proline production, which plays an important role in protecting membrane integrity, photosynthesis, regulating osmotic balance, and activating the ROS scavenging system.…”

Protein kinase gene declines linearly with elevation: a shared genomic feature across species and continents in lichenized fungi suggests role in climate adaptation

“…shown in agave, where a single gene encoding a phosphoenolpyruvate carboxylase enhances the plant's climate resilience (Liu et al, 2021). Not only the gain of genes, but also the loss of genes has been associated with adaptive traits, such as the evolution of particular diets in bats (Blumer et al, 2022).…”

“…While environmental adaptations are commonly highly polygenic (Barghi et al, 2019; Hartke et al, 2021; Pfenninger et al, 2021; Rivas et al, 2018), there is increasing evidence of the effect of single gene content variation (Liu et al, 2021). For example, as has been recently shown in agave, where a single gene encoding a phosphoenolpyruvate carboxylase enhances the plant’s climate resilience (Liu et al, 2021). Not only the gain of genes, but also the loss of genes has been associated with adaptive traits, such as the evolution of particular diets in bats (Blumer et al, 2022).…”