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Cell wall composition strongly influences mesophyll conductance in gymnosperms
Author(s) -
Carriquí Marc,
Nadal Miquel,
ClementeMoreno María J.,
Gago Jorge,
Miedes Eva,
Flexas Jaume
Publication year - 2020
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14806
Subject(s) - cell wall , pectin , biology , cellulose , lignin , secondary cell wall , biophysics , polysaccharide , composition (language) , conductance , botany , thermal diffusivity , middle lamella , xylan , perennial plant , biochemistry , linguistics , philosophy , physics , quantum mechanics , mathematics , combinatorics
Summary Cell wall thickness is widely recognized as one of the main determinants of mesophyll conductance to CO 2 ( g m ). However, little is known about the components that regulate effective CO 2 diffusivity in the cell wall (i.e. the ratio between actual porosity and tortuosity, the other two biophysical diffusion properties of cell walls). The aim of this study was to assess, at the interspecific level, potential relationships between cell wall composition, cell wall thickness ( T cw ) and g m . Gymnosperms constitute an ideal group to deepen these relationships, as they present, on average, the thickest cell walls within spermatophytes. We characterized the foliar gas exchange, the morphoanatomical traits related with g m , the leaf fraction constituted by cell walls and three main components of primary cell walls (hemicelluloses, cellulose and pectins) in seven gymnosperm species. We found that, although the relatively low g m of gymnosperms was mainly determined by their elevated T cw , g m was also strongly correlated with cell wall composition, which presumably sets the final effective CO 2 diffusivity. The data presented here suggest that (i) differences in g m are strongly correlated to the pectins to hemicelluloses and cellulose ratio in gymnosperms, and (ii) variations in cell wall composition may modify effective CO 2 diffusivity in the cell wall to compensate the negative impact of thickened walls. We speculate that higher relative pectin content allows higher g m because pectins increase cell wall hydrophilicity and CO 2 molecules cross the wall dissolved in water.