Abstract Detail

Ecophysiology

Momayyezi, Mina [1], Guy, Robert [1].

Genotypic variation in mesophyll conductance in Populus trichocarpa, Betula papyrifera and Alnus rubra from western North America.

Variation in ecophysiological traits of plant species with wide latitudinal and longitudinal distributions determines possible adaptive capabilities of plant populations to various geoclimatic conditions. Along the path of diffusion of CO₂ from the atmosphere to carboxylation sites in chloroplasts, there is a series of barriers into a leaf including the boundary layer, stomata and components of the mesophyll. We estimated mesophyll conductance (g_m) in Populus trichocarpa, Betula papyrifera, and Alnus rubra genotypes collected from a range of different latitudes in western North America. In separate greenhouse experiments, twelve P. trichocarpa genotypes, ten B. papyrifera populations, and eight A. rubra populations were assessed for g_m using the A-C_i curve method. In P. trichocarpa, g_m increased with latitude and was accompanied by a latitudinal increase in photosynthetic rate (A), leaf N density (mg/mm²), and maximum carboxylation rate by Rubisco (V_max). It is possible that northern P. trichocarpa genotypes with greater A and g_m are physiologically and morphologically adapted to take better advantage of the shorter growing seasons at high latitudes. In contrast, genotypes of a population of B. papyrifera from 59° N latitude showed significantly lower g_m compared to low-latitude populations. That population had greater stomatal density (SD) than low-latitude populations. For A. rubra, g_m did not significantly vary between populations or with latitude. Although leaf mass per unit area (LMA) was positively related to g_m in all three species, no latitudinal pattern was found for LMA. Comparing g_m and related physiological variables we conclude that different sympatric tree species do not show similar broad-scale (i.e., latitudinal) patterns in CO₂ diffusion within their leaves.

1 - University of British Columbia, Forest and Conservation Sciences, Vancouver, British Columbia, V6T 1Z4, Canada

Keywords:
mesophyll conductance
Populus trichocarpa
Betula papyrifera
Alnus rubra
latitude.

Presentation Type: Oral Paper:Papers for Topics
Session: 41
Location: Salon 16/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 10:15 AM
Number: 41001
Abstract ID:1260
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,CSPB President's Award for Best Student Presentation