PT  - JOURNAL ARTICLE
AU  - Raed Elferjani
AU  - Lahcen Benomar
AU  - Mina Momayyezi
AU  - Roberto Tognetti
AU  - Ülo Niinemets
AU  - Raju Y. Soolanayakanahally
AU  - Guillaume Théroux-Rancourt
AU  - Tiina Tosens
AU  - Mebarek Lamara
AU  - Francesco Ripullone
AU  - Simon Bilodeau-Gauthier
AU  - Mohammed S. Lamhamedi
AU  - Carlo Calfapietra
TI  - A meta-analysis of mesophyll conductance to CO<sub>2</sub> in relation to major abiotic stresses in poplar species
AID  - 10.1101/2020.10.19.346270
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.10.19.346270
4099  - http://biorxiv.org/content/early/2020/10/21/2020.10.19.346270.short
4100  - http://biorxiv.org/content/early/2020/10/21/2020.10.19.346270.full
AB  - Mesophyll conductance (gm) determines the diffusion of CO2 from the substomatal cavities to the site of carboxylation in the chloroplasts and represents a critical limiting factor to photosynthesis. In this study, we evaluated the average effect sizes of different environmental constraints on gm in Populus spp., a forest tree model. We collected raw data of 815 A-Ci response curves from 26 datasets to estimate gm, using a single curve-fitting method to alleviate method-related bias. We performed a meta-analysis to assess the effects of different abiotic stresses on gm. We found a significant increase in gm from the bottom to the top of the canopy that was concomitant with the increase of maximum rate of carboxylation and light-saturated photosynthetic rate (Amax). gm was positively associated with increases in soil moisture and nutrient availability, but insensitive to increasing soil copper concentration, and did not vary with atmospheric CO2 concentration. Our results showed that gm was strongly related to Amax and to a lesser extent to stomatal conductance (gs). Also, a negative linear relation was obtained between gm and specific leaf area, which may be used to scale-up gm within the canopy.