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Induction of genes for the stress proteins PR-10 and PAL in relation to growth, visible injuries and stomatal conductance in birch (Betula pendula) clones exposed to ozone and/or drought

Published online by Cambridge University Press:  01 February 1998

E. PÄÄKKÖNEN ,
S. SEPPÄNEN ,
T. HOLOPAINEN ,
H. KOKKO ,
S. KÄRENLAMPI ,
L. KÄRENLAMPI  and
J. KANGASJÄRVI
E. PÄÄKKÖNEN
Affiliation:
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
S. SEPPÄNEN
Affiliation:
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
T. HOLOPAINEN
Affiliation:
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
H. KOKKO
Affiliation:
Department of Biochemistry and Biotechnology, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
S. KÄRENLAMPI
Affiliation:
Department of Biochemistry and Biotechnology, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
L. KÄRENLAMPI
Affiliation:
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland
J. KANGASJÄRVI
Affiliation:
Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland Regional Environment Centre, Bio Teknia L3, 70211 Kuopio, Finland
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Abstract

Well watered (WW) or drought-stressed (DS) saplings of ozone-sensitive and ozone-tolerant (less sensitive) birch (Betula pendula Roth) clones were exposed for 43 d to 0 nl l−1 or 100 nl l−1 ozone. Relative growth rates of leaves, stem, and roots, leaf discolouration, stomatal conductance and induction of genes encoding stress-related proteins PR-10, PAL and a LEA-group protein BP8 were determined. In general, both ozone and drought stress, singly and in combination, increased transcript levels of PR-10 in both clones. This was related to lower induction of PAL (except in older leaves of the tolerant clone), and increased proportions of visibly injured and yellowed leaves in ozone-exposed plants. The clones differed in their stomatal conductance and growth responses. In the less sensitive clone 2, ozone did not affect growth rates, but high stomatal conductance was observed in WW ozone-exposed plants. The more sensitive clone 5 showed, on the contrary, reduced growth rates and low stomatal conductance in WW ozone plants. Interestingly, clone 2 was sensitive to drought stress alone, whereas clone 5 was highly sensitive to ozone and drought stress experienced together. The results show that appearance of visible injuries (necrotic flecks) and enhanced yellowing of leaves coincided with the induction of genes for stress proteins PR-10 and PAL. The short-term growth responses, however, seemed to be separate processes. Additionally, stomatal conductance was related to leaf injuries and growth rates in a complicated manner, emphasizing the complex nature of ozone sensitivity/tolerance mechanisms in birch.

Keywords

Betula pendula Roth (birch)clonesozonedroughtstress proteins
Type
Research Article
Information
The New Phytologist , Volume 138 , Issue 2 , February 1998 , pp. 295 - 305
Copyright
Trustees of the New Phytologist 1998

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