currentsinbiology: Trees recognize roe deer by salivaIn spring, the young, delicate shoots in the fo

currentsinbiology: Trees recognize roe deer by salivaIn spring, the young, delicate shoots in the forest light up, bright and May green. The buds and shoots are the future of the forests as they allow young trees to grow. The problem for the trees is: Roe deer like to eat them, and especially their buds. With a bit of luck, the young, gnawed saplings will only take a few more years to grow than their non-bitten conspecifics. In the worst case, they will become stunted trees, or they will have to give up their fight for survival after a number of years. In this respect, roe deer can cause a great deal of damage and hinder the regeneration of many deciduous tree species.In order to protect themselves against roe deer browsing, trees purposely put up a fight. By studying young beeches (Fagus sylvatica) and maples (Acer pseudoplatanus), biologists from the Leipzig University and the German Centre for Integrative Biodiversity Research (iDiv) have now found out that trees are able to recognise precisely whether a branch or bud has been purposefully nibbled off by a roe deer – or just randomly torn off by a storm or other mechanical disturbance. The saliva of the animals gives them the signal. If a deer feeds on a tree and leaves its saliva behind, the tree will increase its production of salicylic acid. This hormone, in turn, signals to the plant to increase the production of specific tannins. It is known for some of these substances that they influence the feeding behaviour of roe deer, with the result that the deer lose their appetite for the shoots and buds. In addition, the saplings increase their concentrations of other plant hormones, growth hormones in particular. These hormones enhance the growth of the remaining buds to compensate for the lost ones.Ohse, B., Hammerbacher, A., Seele, C., Meldau, S., Reichelt, M., Ortmann, S. and Wirth, C. (2016), Salivary cues: simulated roe deer browsing induces systemic changes in phytohormones and defence chemistry in wild-grown maple and beech saplings. Functional Ecology. doi:10.1111/1365-2435.12717 Published online on 8. August 2016. Caption: Two of the study co-authors, the scientists Carolin Seele (Leipzig University) and Stefan Meldau (Max-Planck-Institute for Chemical Ecology) collect buds for the subsequent analysis of plant hormones and tannins. Credit: Bettina OhseCertain trees have evolved biochemical responses to deer saliva!! Biology is nuts. -- source link

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