Developmental changes in mesophyll diffusion conductance and photosynthetic capacity under different light and water availabilities in Populus tremula: how structure constrains function

Abstract

Finite mesophyll diffusion conductance (gm) significantly constrains net assimilation rate (An), but gm variations and variation sources in response to environmental stresses during leaf development are imperfectly known. The combined effects of light and water limitations on gm and diffusion limitations of photosynthesis were studied in saplings of Populus tremula L. An one-dimensional diffusion model was used to gain insight into the importance of key anatomical traits in determining gm. Leaf development was associated with increases in dry mass per unit area, thickness, density, exposed mesophyll (Smes/S) and chloroplast (Sc/S) to leaf area ratio, internal air space (fias), cell wall thickness and chloroplast dimensions. Development of Smes/S and Sc/S was delayed under low light. Reduction in light availability was associated with lower Sc/S, but with larger fias and chloroplast thickness. Water stress reduced Sc/S and increased cell wall thickness under high light. In all treatments, gm and An increased and CO2 drawdown because of gm, Ci-Cc, decreased with increasing leaf age. Low light and drought resulted in reduced gm and An and increased Ci-Cc. These results emphasize the importance of gm and its components in determining An variations during leaf development and in response to stress.

Relationships of Leaf Net Photosynthesis, Stomatal Conductance, and Mesophyll Conductance to Primary Metabolism: A Multispecies Meta-Analysis Approach

“…These approaches comprise (1) the "Harley" method, combining chlorophyll fluorescence and gasexchange data (Harley et al, 1992); (2) the "Ethier" curve-fitting method (Ethier and Livingston, 2004); and (3) the "Evans" method, employing an online carbon isotope discrimination methodology (Evans et al, 1986). There is another approach to estimate g m in a manner based on leaf anatomical properties, which agrees with in vivo approaches in several angiosperms as well as in several fern species (Tosens et al, 2012;Tomás et al, 2013;Carriquí et al, 2015). However, several concerns were recently published about the reliability and uncertainties of the different in vivo methodologies (Tholen et al, 2012;Sun et al, 2014).…”

Generality of relationships between leaf pigment contents and spectral vegetation indices in Mallorca (Spain)

“…In that case, besides spongy tissue that favors light scattering, palisade cells canalize light into lower mesophyll layers (Vogelmann et al 1996;Smith et al 1997). Moreover, the leaf thickness influences in the number of cells per leaf area, and consequently, the chlorophyll content (Tosens et al 2012).…”

Effect of waterlogging on boreal forest tree seedlings during dormancy and early growing season

“…In addition, mesophyll diffusion conductance of CO 2 from sub-stomatal cavities to chloroplasts (g m ) is a key trait affecting photosynthesis (Evans et al 2009;Niinemets et al 2009;Terashima et al 2011). Leaf anatomical traits such as cell wall thickness and chloroplast distribution, which are affected by environmental stress, are determinants of mesophyll conductance (Flexas et al 2012;Tosens et al 2012;Flexas et al 2014). …”

“…Thus it is possible that the leaves of growth waterlogged pubescent birch seedlings were thicker compared to the controls but this kind of thickening did not occur in silver birch. The thicker and smaller leaves have less intercellular areas and increased amount of palisade or spongy mesophyll cells that tolerate stressful conditions like high irradiation, cold weather, drought and flooding (Guerfel et al 2009;Tosens et al 2012;Zhang et al 2012). Contrary to pubescent birch, a smaller leaf area in silver birch was accompanied by smaller biomass, which is probably connected to root damage in DW and DWGW.…”