Loss of Function of Rice Plastidic Glycolate/Glycerate Translocator 1 Impairs Photorespiration and Plant Growth

Abstract

Ribulose-1,5-bisphosphate carboxylase/oxygenase, the key enzyme of photosynthetic carbon fixation, is able to accept both O 2 and CO 2 as substrates. When it fixes O 2 , it produces 2-phosphoglycolate, which is detoxified by photorespiration and recycled to the Calvin-Benson-Bassham cycle. To complete photorespiration, metabolite transport across three organelles, chloroplasts, peroxisomes, and mitochondria, is necessary through transmembrane transporters. In rice (Oryza sativa) little is known about photorespiratory transmembrane transporters. Here, we identified the rice plastidic glycolate/glycerate translocator 1 (OsPLGG1), a homolog of Arabidopsis PLGG1. OsPLGG1 mutant lines, osplgg1-1, osplgg1-2, and osplgg1-3, showed a growth retardation phenotype, such as pale green leaf, reduced tiller number, and reduced seed grain weight as well as reduced photosynthetic carbon reduction rate due to low activities of photosystem I and II. The plant growth retardation in osplgg1 mutants was rescued under high CO 2 condition. Subcellular localization of OsPLGG1-GFP fusion protein, along with its predicted Nterminal transmembrane domain, confirmed that OsPLGG1 is a chloroplast transmembrane protein. Metabolite analysis indicated significant accumulation of photorespiratory metabolites, especially glycolate and glycerate, which have been shown to be transported by the Arabidopsis PLGG1, and changes for a number of metabolites which are not intermediates of photorespiration in the mutants. These results suggest that OsPLGG1 is the functional plastidic glycolate/glycerate transporter, which is necessary for photorespiration and growth in rice.

Mixotrophic growth of the extremophile Galdieria sulphuraria reveals the flexibility of its carbon assimilation metabolism

“…(2012) and Shim et al . (2020). Identification of metabolites was performed with MassHunter Qualitative (v.b08.00; Agilent Technologies, Santa Clara, CA, USA) by comparing spectra to the NIST14 Mass Spectral Library (https://www.nist.gov/srd/nist-standard-reference-database-1a-v14) and to a quality control sample containing all target compounds.…”

“…For GC-MS analysis the samples were prepared and analyzed as described by Gu et al (2012) and Shim et al (2020). Identification of metabolites was performed with MASSHUNTER Qualitative (v.b08.00; Agilent Technologies, Santa Clara, CA, USA) by comparing spectra to the NIST14 Mass Spectral Library (https://www.…”

Topological Analysis of the Carbon-Concentrating CETCH Cycle and a Photorespiratory Bypass Reveals Boosted CO2-Sequestration by Plants

“…We conducted our analysis with 100% inhibition of the glycolate transportation to the peroxisome, acknowledging the fact that complete inhibition of photorespiration might be detrimental for plants ( Peterhansel et al, 2013 ). It is also of concern that how well the system would work in the absence of PLGG1 that would lead to the accumulation of glycolate in the chloroplast, which is toxic to the plant ( Shim et al, 2019 ; South et al, 2019 ; Cui et al, 2021 ). In this context, 80% suppression of PLGG1 in South et al (2019) still allows a lower amount of photorespiratory activity, while our model inhibits all photorespiration to estimate the maximum possible effects (Supplementary text).…”

Identification of a Saltol-independent Salinity Tolerance Polymorphism in Rice Mekong Delta Landraces and Characterization of a Promising Line, Doc Phung

“…LOC_Os01g32830 encodes a predicted chloroplast-localized transmembrane protein: chloroplast glycolate/glycerate translocator 1 (OsPLGG1). (Shim et al 2019). PLGG1 transports glycolate/glycerate produced in chloroplasts to peroxisomes during photorespiration (Pick et al 2013).…”