Xiaotong Jiang

Date: April 16, 2024

Time: 12:00 pm

In-person location: 168 PLB

Zoom: https://bit.ly/prltuesnoon
Meeting ID: 957 9659 6975
Passcode: 420205

Speaker: Xiaotong Jiang

Lab: Hu lab

Title: Arabidopsis Glyoxylate Reductase 1 is involved in a non-canonical photorespiratory pathway under high light conditions 

Abstract: Photorespiration is a physiological process that occurs simultaneously with photosynthesis in plants, which is often considered wasteful. However, photorespiration involves the coordination of multiple organelles and connects with various primary metabolic pathways, thus its responses to the environment can greatly influence the fate of plants. Plants in nature experience high light conditions frequently, but the role of photorespiration in plant interaction with high light is still not very clear. Our previous studies found several Arabidopsis photorespiratory mutants that only exhibited obvious photosynthetic phenotypes under high and dynamic light conditions. To identify potential modulators of photorespiration under such conditions, we performed a genetic screen for suppressors of the photorespiratory mutant, hpr1, which is defective in the peroxisomal hydroxypyruvate reductase 1. A suppressor that partially rescued the small rosette and deficient photosynthetic performance of the hpr1 mutant was mapped to GLYR1, which encodes the cytosolic glyoxylate reductase 1 that catalyzes the conversion of glyoxylate to glycolate. Independent loss-of-function alleles of GLYR1 also recapitulated the partial rescue of hpr1 in plant appearance, as well as photosynthetic and photorespiratory activities measured by the dynamic environmental photosynthesis imager and gas chromatography-mass spectrometry. Interestingly, glyr1 also suppressed the phenotypes of the photorespiratory mutant catalase 2, but not a null allele of the Plastidic Glycolate Glycerate Transporter 1. Our data revealed a possible connection between glyoxylate reduction in the cytosol and a non-canonical branch of the photorespiratory pathway mediated by the cytosolic HPR2 enzyme, suggesting the metabolic flexibility of photorespiration that may help photosynthesis and plant growth under stressful conditions. Our discovery may provide a foundation for agricultural efforts to improve crop performance in response to the high light environment.