Mapping of drought-induced changes in tissue characteristics across the leaf profile of Populus balsamifera

Authors: MOMAYYEZI, MINA - University Of California, Davis; CHU, CHEYENNE - University Of British Columbia; STOBBS, JARVIS - Canadian Light Source Inc; SOOLANAYAKANAHALLY, RAJU - Agri Food - Canada; GUY, ROBERT - University Of British Columbia; McElrone, Andrew; KNIPFER, THORSTEN - University Of British Columbia

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2024
Publication Date: 12/18/2024
Citation: Momayyezi, M., Chu, C., Stobbs, J.A., Soolanayakanahally, R.Y., Guy, R.D., McElrone, A.J., Knipfer, T.M. 2024. Mapping of drought-induced changes in tissue characteristics across the leaf profile of Populus balsamifera. New Phytologist. 245:534-545. https://doi.org/10.1111/nph.20240.
DOI: https://doi.org/10.1111/nph.20240

Interpretive Summary:

Technical Abstract: Optimum leaf performance demands effective movement of gases and water in three-dimensional space through leaf internal structure. However, the structure-function relationship between mesophyll, bundle sheath extensions (BSEs), and vein area during gas exchange and water transport, under various hydration status is remained mostly unknown across woody species. In this study, we elucidate Populus balsamifera L. leaf structure sensitivity to water stress by analyzing genotype-specific changes in distribution profiles for leaf internal characteristics under dehydration and following re-watering. Using X-ray microcomputed tomography, our data indicates that genotype Carnduff-9 (CAR-9, native to 49° N latitude) has thicker leaves, lower cell packing and greater mesophyll porosity under well-watered condition compared to Gillam-5 (GIL-5, native to 56º N latitude). Under dehydration, CAR-9 exhibited a reduction in mesophyll porosity across the leaf profile, which was irreversible after re-watering. In contrast, GIL-5 with thinner leaves, higher cell packing, thicker palisade layer and less mesophyll porosity, showed an increase in mesophyll porosity under dehydration which fully recovered after re-watering. Dehydration impacted vein area distribution differently in each genotype. GIL-5 leaves with more BSEs provided a rigid structure and restored the vein area distribution after re-watering, while dehydration-induced changes in the vein area distribution for CAR-9 showed no recovery after re-watering. Differences in dehydration-induced response between the genotypes studied here were linked to inherent differences in mesophyll cell arrangement, porosity between the cells, and BSEs. Rehydration was closely related to mesophyll cell packing and porosity distribution. In conclusion, GIL-5 leaf structure with less porosity and more BSEs area exhibited less dehydration-induced changes in mesophyll with a greater recovery in leaf thickness mostly through lower spongy after re-watering.