JXB Advance Access originally published online on March 20, 2007
Journal of Experimental Botany 2007 58(7):1783-1793; doi:10.1093/jxb/erm038
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RESEARCH PAPER |
Simultaneous growth and emission measurements demonstrate an interactive control of methanol release by leaf expansion and stomata
1Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
2Institute for Chemistry and Dynamics of the Geosphere:Phytosphere (ICG III), Research Centre Jülich, 52425 Jülich, Germany
3Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 64, Tartu 51014, Estonia
* To whom correspondence should be addressed. E-mail: shueve{at}gmx.de
Emission from plants is a major source of atmospheric methanol. Growing tissues contribute most to plant-generated methanol in the atmosphere, but there is still controversy over biological and physico-chemical controls of methanol emission. Methanol as a water-soluble compound is thought to be strongly controlled by gas-phase diffusion (stomatal conductance), but growth rate can follow a different diurnal rhythm from that of stomatal conductance, and the extent to which the emission control is shared between diffusion and growth is unclear. Growth and methanol emissions from Gossypium hirsutum, Populus deltoides, and Fagus sylvatica were measured simultaneously. Methanol emission from growing leaves was several-fold higher than that from adult leaves. A pronounced diurnal rhythm of methanol emission was observed; however, this diurnal rhythm was not predominantly determined by the diurnal rhythm of leaf growth. Large methanol emission peaks in the morning when the stomata opened were observed in all species and were explained by release of methanol that had accumulated in the intercellular air space and leaf liquid pool at night in leaves with closed stomata. Cumulative daily methanol emissions were strongly correlated with the total daily leaf growth, but the diurnal rhythm of methanol emission was modified by growth rate and stomatal conductance in a complex manner. While in G. hirsutum and in F. sylvatica maxima in methanol emission and growth coincided, maximum growth rates of P. deltoides were observed at night, while maximum methanol emissions occurred in the morning. This interspecific variation was explained by differences in the share of emission control by growth processes, by stomatal conductance, and methanol solubilization in tissue water.
Key words: Fagus sylvatica, Gossypium hirsutum, leaf growth, methanol emission, Populus deltoides, stomatal conductance
Received 6 November 2006; Revised 25 January 2007 Accepted 8 February 2007