Biomass and yield in solanum lycopersicum expressing a synthetic photorespiration pathway

Authors: DOUGHERTY, LAURA - Former ARS Employee; Cooper, Bret; Vinyard, Bryan; Bunce, James; Stommel, John

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2024
Publication Date: 1/27/2025
Citation: Dougherty, L., Cooper, B., Vinyard, B.T., Bunce, J.A., Stommel, J.R. 2025. Biomass and yield in solanum lycopersicum expressing a synthetic photorespiration pathway. Journal of the American Society for Horticultural Science. 150(1):34–41. https://doi.org/10.21273/JASHS05448-24.
DOI: https://doi.org/10.21273/JASHS05448-24

Interpretive Summary: Agricultural advancements during the Green Revolution and development of high yielding crop varieties has been critical for growth in food production. To meet the demand of the growing world population, it is estimated that crop yield needs to increase by 70% from 2007-2050. Researchers have turned their attention to improving efficiency of photosynthesis and photorespiration to increase crop yield. This study explored whether a modified photorespiratory pathway demonstrated to reduce photorespiratory metabolic energy demands and increase plant biomass in model species could boost tomato crop yield, notably yield of marketable fruit. Tomato plants were transformed with three modified genes from the photorespiratory pathway and yield trials assessing vegetative biomass and fruit yield were conducted. Plants expressing the modified metabolic pathway were larger and exhibited up to 63% increased biomass. The number of fruit was similarly greater (1.4 to 4.2-fold) in modified plants, however, average individual fruit weights were significantly less for most plants. Further study is needed to direct energy savings realized from the modified photorespiratory pathway away from vegetative plant growth towards enhanced marketable fruit yield. These research findings will benefit researchers active in crop improvement research.

Technical Abstract: Considerable interest exists in improving the efficiency of photosynthesis and photorespiration to increase crop yields that will address growing world food needs. The current study investigated whether a novel synthetic photorespiratory pathway demonstrated to reduce photorespiratory metabolic energy demands and increase plant vegetative biomass in model species could boost tomato crop yield, notably yield of marketable fruit. The tomato cultivar Moneymaker was transformed with a synthetic photorespiration pathway construct containing a Cucurbita maxima malate synthase (MS) gene and a Chlamydomonas reinhardtii glycolate dehydrogenase (CrGDH) gene targeted to the chloroplast, with a plastidal glycolate glycerate translocator 1 (PLGG1) hairpin interference construct targeting the native photorespiratory pathway. Plants of seven T2 generation lines from independent transformation events expressed the MS and CrGDH transgenes, while having at least 3-fold reduction of native PLGG1 expression relative to non-transformed Moneymaker. Plants from transformed lines were larger and exhibited up to 63% increased biomass in comparison to the Moneymaker control. The number of fruit was similarly greater (1.4 to 4.2-fold) in modified plants, however, average individual fruit weights were significantly less for all but one line. Among transformed lines, larger fruited lines had the lowest biomass, while the smaller fruited lines had the highest biomass. Values for VCmax and Jmax derived from CO2 assimilation curves were statistically similar or lower in transformants relative to the control. Metabolic profiles obtained from HPLC-MS analysis revealed increases in small-chain and medium-chain fatty acids, and jasmonate derivatives. Principle component analysis of metabolite profiles separated transformants into two groups distinguished by total biomass and fruit size. Observed increases in plant biomass in transformed lines suggests that energy savings were realized from reduced photorespiration but was directed towards vegetative growth. Further studies to balance vegetative vs. reproductive biomass and exploit higher fruit counts observed in transformants may be beneficial for enhanced fruit yield.