Abstract Detail


Momayyezi, Mina [1], McElrone, Andrew [2].

Structural and functional leaf diversity explain variation in photosynthetic capacity across J. regia accessions.

Differences in leaf structural and functional characteristics determine photosynthesis and associated responses to the environment under inherent and induced conditions. In walnut nut production, only a few Juglans regia cultivars are dominantly used as scions, and this raises concerns about the low genetic diversity and high risk of susceptibility to abiotic and biotic stressors. Germplasm collections hold potential for improving stress tolerance and developing new crops. We explored the anatomical and biochemical bases of photosynthetic capacity and dehydration response in Juglans spp. and also across J. regia accessions in the USDA-ARS National Clonal Germplasm. Using X-ray microcomputed tomography, we found a parallel shift in mesophyll thickness and porosity concurrent with gas exchange responses in J. regia accessions. Net assimilation rate (An) differed significantly among accessions. Higher stomatal conductance and mesophyll conductance, leaf thickness, mesophyll porosity, gas-phase diffusion, and leaf nitrogen, and lower leaf mass and stomatal density supported higher An in J. regia accessions. High CO2-saturated assimilation rates led to increases in An under diffusional and biochemical limitations. Accessions native to the lower latitude had greater An from habitats with more frost-free days, greater precipitation seasonality, and lower temperature seasonality. Water stress reduced photosynthesis more in the lower latitude accessions, which exhibited the highest An under well-watered conditions. However, those accessions maintained their An the highest under dehydration. J. regia accessions with prominent leaf structural and biochemical traits and enhanced photosynthesis, are suitable candidates for commercial breeding.

1 -
2 - University of California Davis, 2154 RMI North, Department of Viticulture & Enology Department, University of California Davis, Davis, California, 95616, United States

leaf traits
Leaf anatomy
CO2 diffusion
Photosynthetic capacity

Presentation Type: Oral Paper
Number: EPH2002
Abstract ID:989
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

Copyright © 2000-2022, Botanical Society of America. All rights reserved