Leaf Volatile Emissions of Betula pendula during Autumn Coloration and Leaf Fall

Abstract

Deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. It has been suggested that aphids may use volatile organic compounds (VOCs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. We analyzed VOCs emitted by the foliage of Betula pendula Roth. during autumn coloration and from leaf litter just after leaf fall. We tested the hypothesis that costly, photosynthesis-related terpenes and other herbivore-induced VOCs related to attraction of aphid parasitoids and predators are reduced during the coloration process. We also investigated if the VOC emission profile of abscising leaves is different from that of early stage yellowing leaves. Enemy-luring compounds (E)-β-ocimene, linalool, and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted only from the green foliage. Methyl salicylate (MeSa), known to recruit predatory bugs and attract migrant aphids, was emitted until the first stage of color change. Cis-3-hexenol, an indicator of cellular disintegration, became dominant in the emissions from abscising leaves and from fresh leaf litter. We discuss the ecological significance of the observed changes in birch leaf VOC profiles during the process of autumn senescence.

Do Insectivorous Birds use Volatile Organic Compounds from Plants as Olfactory Foraging Cues? Three Experimental Tests

“…Even though abscising leaves emit VOCs, their emissions are mostly dominated by GLVs (Holopainen et al. ), and thus, the possible VOC emissions from withered branches were likely less diverse and probably had lower compound concentrations than those of living trees.…”

Genotypic variation in yellow autumn leaf colours explains aphid load in silver birch

“…, 1998). As the association between the aphid abundance and N loss further seems to take place at the tree genotype level, this may cause additional selection pressure on those silver birch attributes, such as volatile emissions (Holopainen et al. , 2010; Powell et al.…”

“…Autumnal nutrient resorption has a major effect on tree growth and fitness (May & Killingbeck, 1992) and B. pendula spring leaf growth, for example, can exclusively rely on internal cycling for 2 wk after bud burst (Millard et al, 1998). As the association between the aphid abundance and N loss further seems to take place at the tree genotype level, this may cause additional selection pressure on those silver birch attributes, such as volatile emissions (Holopainen et al, 2010;Powell et al, 2006), that are not related to leaf colouration but may affect aphid load in trees in the autumn.…”

Green Leaf Volatile Emissions during High Temperature and Drought Stress in a Central Amazon Rainforest

“…Following the degredation of HPLA (by a hydroperoxide lyase), a number of volatile oxylipins are produced which are termed green leaf volatiles (GLVs), including C 6 aldehydes, alcohols, and their corresponding acetate esters [ 23 , 24 , 25 , 26 ]. Under controlled laboratory studies, the emissions of GLVs from plants have been documented following a number of abotic and biotic stresses associated with ROS accumulation, including pathogen attack [ 27 ], high ambient ozone concentrations [ 22 , 28 ], herbivory [ 29 ], desiccation [ 30 ], high light and temperature [ 31 ], mechanical wounding [ 25 ], light-dark transitions [ 32 ], freeze-thaw events [ 33 ], and programmed cell death during senescence [ 34 ]. However, GLVs are rarely reported from field observations in natural ecosystems, particularly in the tropics during environmental extremes.…”