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Substantial role for carbonic anhydrase in latitudinal variation in mesophyll conductance of Populus trichocarpa Torr. & Gray
Author(s) -
Momayyezi Mina,
Guy Robert D.
Publication year - 2017
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12851
Subject(s) - populus trichocarpa , acetazolamide , carbonic anhydrase , cline (biology) , photosynthesis , stomatal conductance , chemistry , botany , chlorophyll fluorescence , biology , biochemistry , gene , enzyme , physiology , population , demography , genome , sociology
Abstract In Populus trichocarpa (black cottonwood), net photosynthesis ( A n ) varies with latitude and, in northern genotypes, is supported by higher stomatal conductance ( g s ). We report here a parallel cline in mesophyll conductance ( g m ) and link this variation to carbonic anhydrase (CA) activity. Using concurrent carbon isotope discrimination and chlorophyll fluorescence methods, we examined the effects of acetazolamide, an inhibitor of CA, on g m in six representative genotypes (three from either end of the north‐south cline). Acetazolamide reduced CA activity, g m , g s , chloroplast CO 2 concentration ( C c ) and A n at normal CO 2 (400 μ mol mol −1 ), the latter being reversible at saturating CO 2 . Absolute reductions in A n , g m and CA activity were greater in northern genotypes than in southern genotypes ( P < 0.025) but percent reductions were similar. In contrast, northern genotypes showed lower percent reduction in C c compared to southern genotypes ( P < 0.025). The northern genotypes had greater CA activity relative to both leaf area (two‐fold) and mass (1.8‐fold) ( P < 0.016). The relationship between CA activity and g m was similar whether the variation was inherent or inhibitor induced. We suggest that greater CA activity contributes to higher g m in northern P. trichocarpa genotypes, but other diffusion pathway components may also be involved.