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Augmentation of abscisic acid (ABA) levels by drought does not induce short-term stomatal sensitivity to CO2 in two divergent conifer species


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McAdam, SAM, Brodribb, TJ, Ross, JJ and Jordan, GJ 2011 , 'Augmentation of abscisic acid (ABA) levels by drought does not induce short-term stomatal sensitivity to CO2 in two divergent conifer species' , Journal of Experimental Botany, vol. 62, No. 1 , pp. 195-203 , doi: 10.1093/jxb/erq260.

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The stomata of conifers display very little short-term response to changes in atmospheric CO2 concentration (Ca),
whereas the stomatal responses of angiosperms to Ca increase in response to water stress. This behaviour of
angiosperm stomata appears to be dependent on foliar levels of abscisic acid (ABAf). Here two alternative
explanations for the stomatal insensitivity of conifers to Ca are tested: that conifers have either low ABAf or a higher
or absent threshold for ABA-induced sensitivity. The responsiveness of stomatal conductance (gs) to a sequence of
transitions in Ca (386, 100, and 600 mmol mol21) was recorded over a range of ABAf in an angiosperm and two
divergent conifer species. The different ABA levels were induced by a mild drought cycle. Although the angiosperm
and conifer species showed similar proportional increases in ABAf following drought, conifer stomata remained
insensitive to changes in Ca whereas angiosperm stomata showed enhanced sensitivity with increasing ABAf. The
conifers, however, had much higher ABAf prior to drought than the angiosperm species, suggesting that nonsensitivity
to Ca in these conifers was due to an absent or inactive response/signalling pathway rather than
insufficient ABAf.

Item Type: Article
Authors/Creators:McAdam, SAM and Brodribb, TJ and Ross, JJ and Jordan, GJ
Keywords: Abscisic acid angiosperm carbon dioxide conifer drought stomata stomatal conductance
Journal or Publication Title: Journal of Experimental Botany
ISSN: 0022-0957
DOI / ID Number: 10.1093/jxb/erq260
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