Population-specific responses of floral volatiles to abiotic factors in changing environments

Authors: KEEFOVER-RING, KEN - University Of Wisconsin; HETHERINGTON, MATTHEW - University Of Wisconsin; Brunet, Johanne

Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2022
Publication Date: 4/28/2022
Citation: Keefover-Ring, K., Hetherington, M., Brunet, J. 2022. Population-specific responses of floral volatiles to abiotic factors in changing environments. American Journal of Botany. 109(5):676-688. https://doi.org/10.1002/ajb2.1846.
DOI: https://doi.org/10.1002/ajb2.1846

Interpretive Summary: Pollinators are needed for seed production of many plants, including both crops and non-crop species. Changes in water availability and temperature are expected under climate change and it is important to determine the impact of such changes on plants and their pollinators. In this study, we examined the impact of water availability on floral volatiles, compounds emitted by flowers that play an important role in pollinator attraction. We examined the phenotypic response of floral volatiles to water availability and compared such response among populations of a plant species. A phenotypic response is one way that plants can rapidly adjust to shifts in abiotic conditions associated with climate change. We also determined the impact of water on floral volatiles at two distinct temperatures for one population. Finally, we compared day and evening emission of floral volatiles because some pollinators occur mostly at dusk. We detected a phenotypic response of floral volatiles to water availability and the phenotypic response differed among populations. For example, the emission of some floral volatiles increased under drier conditions in two populations but decreased in the other population. Such population-specific phenotypic responses of floral volatiles to water makes general predictions on the impact of climate change on floral volatiles and on pollinator attraction difficult. However, the population variation in phenotypic plasticity in our experiment indicates genetic variation for phenotypic plasticity among populations. Phenotypic plasticity to abiotic factors would permit crops to adjust quickly to environmental changes. The presence of genetic variation in phenotypic plasticity implies that this trait can be selected on. These results have important implications for crop production under climate change. If genetic variation in phenotypic plasticity exists among crop cultivars, phenotypic plasticity to abiotic factors could be used in breeding programs to help crops adjust quickly to a wider range of environmental conditions. This information should benefit plant breeders, scientists and regulators interested in the impact of global change on plants, including crops.

Technical Abstract: Changes in water availability associated with climate change can affect many plant traits, including floral volatiles involved in pollinator attraction. To examine whether floral volatiles responded to water availability, and whether this phenotypic plasticity differed among populations, we grew Rocky Mountain columbine plants (Aquilegia coerulea), started from seeds collected in three wild populations in Colorado (CO), Utah, and Arizona, under two moisture regimes. We observed a phenotypic response to water availability, with an increase in three volatile organic compounds (VOCs) in the wetter environment. Moreover, the phenotypic response of six VOCs to water differed among populations. Emissions of alpha-thujene, (-)-alpha-pinene, and (+)-ß-pinene, for example, increased under drier conditions for the CO and UT populations but decreased for the AZ population. When plants from the CO population were grown under the two water regimes (wet and dry) at 20° C (cool) or 25.5º C (warm) daytime temperature, there was no phenotypic response of VOC to water at either temperature. Finally, when comparing day to evening emission rates of VOCs for plants from the wet treatment in the cool room, emission of most individual compounds was greater during the day. The population-specific phenotypic responses of floral volatiles to water complicate predictions of the effects of climate change on a plant and its pollinators.