Structural and functional leaf diversity lead to variability in photosynthetic capacity across a range of Juglans regia genotypes

Authors: MOMAYYEZI, MINA - University Of California, Davis; Rippner, Devin; DUONG, FIONA - University Of California, Davis; RAJA, PRANAV - University Of California, Davis; BROWN, PATRICK - University Of California, Davis; Kluepfel, Daniel; EARLES, J. MASON - University Of California, Davis; FORRESTEL, ELISABETH - University Of California, Davis; GILBERT, MATTHEW - University Of California, Davis; McElrone, Andrew

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2022
Publication Date: 6/1/2022
Citation: Momayyezi, M., Rippner, D.A., Duong, F.V., Raja, P.V., Brown, P.J., Kluepfel, D.A., Earles, J., Forrestel, E.J., Gilbert, M.E., McElrone, A.J. 2022. Structural and functional leaf diversity lead to variability in photosynthetic capacity across a range of Juglans regia genotypes. Plant Cell and Environment. 45(8):2351-2365. https://doi.org/10.1111/pce.14370.
DOI: https://doi.org/10.1111/pce.14370

Interpretive Summary:

Technical Abstract: Similar to other cropping systems, few cultivars are used as scion in commercial walnut production. Germplasm collections can be used to diversify cultivar options and hold potential for improving crop productivity and stress tolerance. Variability in leaf structural and functional characteristics drive inherent and stress-induced differences in photosynthetic capacity even within a species. In this study we explored the anatomical and biochemical bases of photosynthetic capacity using X-ray microcomputed tomography, gas exchange and leaf chemical analysis in 11 J. regia accessions in the National Clonal Germplasm Repository located in Winters, California. These accessions have distinct genetic divergence and originate from different latitudes with varying temperature and precipitation gradients. Net assimilation rate (An) differed significantly among accessions and was greater in those from lower latitudes coincident with increases in stomatal and mesophyll conductance (gs, gm), leaf thickness, mesophyll porosity and gas-phase diffusion, leaf mass and nitrogen, and stomatal density. CO2-saturated assimilation rates were consistent with patterns in An. Greater An was found in accessions native to climates with more frost-free days and greater precipitation seasonality but lower temperature seasonality in lower latitudes. As expected, water stress consistently impaired photosynthesis with the highest % reductions in three lower latitude accessions (A3, A5, and A9), which had the highest assimilation rates under well-watered conditions. However, absolute An remained equal to all accessions for A3 and A5 under dehydration. J. regia accessions originating from lower latitudes, which have leaf structural traits and biochemistry that enhance photosynthesis, could be used as commercial scions or breeding parents for greater productivity.