Priming With The Green Leaf Volatile (Z)-3-Hexeny-1-yl Acetate Enhances Drought Resistance in Wheat Seedlings

It was reported that green leaf volatiles play vital roles in multiple plant biotic and abiotic stresses, however, their functions in drought resistance have not been determined. The present study was to investigate the possible role of (Z)-3-hexeny-1-yl acetate (Z-3-HAC), a kind of green leaf volatile, in alleviating wheat drought stress and the underlying physiological mechanisms governing this effect. Seedlings of a drought-resistant variety were primed with 100 μM Z-3-HAC at the four-leaf stage before drought treatment. Morphological analysis showed that the primed seedlings grew better and possessed higher biomass accumulation in both shoot and root under drought stress. Additionally, exogenous Z-3-HAC significantly increased the total root length, total root surface area, and total root volume of the seedlings under drought stress. Physiological measurements showed that the primed seedlings possessed higher relative water content (RWC), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximal photochemical efficiency of photosystem II (PSII) (Fv/Fm), photochemical activity of PSII (Fv′/Fm′), total chlorophyll content, activities of the antioxidant enzymes, and osmolyte accumulation under drought conditions. Furthermore, relative electrolyte conductivity (REC), intercellular CO2 concentration (Ci), reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content were significantly lower than in non-primed seedlings. Lastly, principal component analysis (PCA) indicated that Z-3-HAC protects wheat seedlings against damage from drought stress mainly through antioxidant and osmoregulation systems.

Smell of green leaf volatiles attracts white storks to freshly cut meadows

Finding food is perhaps the most important task for all animals. Birds often show up unexpectedly at novel food sources such as freshly tilled fields or mown meadows. Here we test whether wild European white storks primarily use visual, social, auditory or olfactory information to find freshly cut farm pastures where insects and rodents abound. Aerial observations of an entire local stork population documented that birds could not have become aware of a mown field through auditory, visual or social information. Only birds within a 75° downwind cone over 0.4–16.6 km approached any mown field. Placing freshly cut grass from elsewhere on selected unmown fields elicited similarly immediate stork approaches. Furthermore, uncut fields that were sprayed with a green leaf volatile organic compound mix ((Z)-3-hexenal, (Z)-3-hexenol, hexenyl acetate), the smell of freshly cut grass, immediately attracted storks. The use of long-distance olfactory information for finding food may be common in birds, contrary to current perception.

Dispensing a Synthetic Green Leaf Volatile to Two Plant Species in a Common Garden Differentially Alters Physiological Responses and Herbivory

Herbivore-induced plant volatile (HIPV)-mediated eavesdropping by plants is a well-documented, inducible phenomenon that has practical agronomic applications for enhancing plant defense and pest management. However, as with any inducible phenomenon, responding to volatile cues may incur physiological and ecological costs that limit plant productivity. In a common garden experiment, we tested the hypothesis that exposure to a single HIPV would decrease herbivore damage at the cost of reduced plant growth and reproduction. Lima bean (Phaseolus lunatus) and pepper (Capsicum annuum) plants were exposed to a persistent, low dose (~10 ng/h) of the green leaf volatile cis-3-hexenyl acetate (z3HAC), which is a HIPV and damage-associated volatile. z3HAC-treated pepper plants were shorter, had less aboveground and belowground biomass, and produced fewer flowers and fruits relative to controls, while z3HAC-treated lima bean plants were taller and produced more leaves and flowers than did controls. Natural herbivory was reduced in z3HAC-exposed lima bean plants, but not in pepper. Cyanogenic potential, a putative direct defense mechanism in lima bean, was lower in young z3HAC-exposed leaves, suggesting a growth–defense tradeoff from z3HAC exposure alone. Plant species-specific responses to an identical volatile cue have important implications for agronomic costs and benefits of volatile-mediated interplant communication under field conditions.