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An international research team lead by Ülo Niinemets, professor of plant physiology at the Estonian University of Life Sciences has come to the conclusion that climate change towards more humid and warm may lead to greater volatile emissions from plants, also affecting the chemical composition of the atmosphere.

Global warming at northern latitudes is expected not only to increase temperature, but also to result in greater air humidity which together can lead to more favourable conditions for growth of pathogenic fungi. So far, the effects of such a possible enhancement of fungal spread on foliage functioning and volatile emissions have not been studied quantitatively. Autumns of 2011 and 2013 in Estonia were exceptionally humid and there was a massive spread of oak powdery mildew (Erysiphe alphitoides) on oaks (Quercus robur) with virtually every leaf on every tree being infected. The plant physiology research team at the Estonian University of Life Sciences demonstrated that powdery mildew infection in oak is associated with infection-dependent reductions in photosynthesis, and isoprene emission and with major increases in stress-induced emissions. This is the first study demonstrating that the degree of infection by pathogenic fungi is quantitatively associated with the release of stress-induced volatiles, and suggests that future warmer and more humid conditions are associated with greater release of stress volatiles. These volatiles play important roles in atmospheric chemistry and thus, enhanced biotic stress in future conditions might have important impacts on atmospheric chemistry. The study was published in December issue of top tree functional biology journal “Tree Physiology”.