Influence of drought stress on the metabolite and ion composition in nectar and nectaries of different day- and night-flowering Nicotiana species.

Abstract

The frequencies of droughts worldwide will increase in the future due to climate changes. Nectar composition of plant species varies in relation to pollinator and can also be influenced by drought. We investigated both different pollinated species and the effects of drought in parallel. In addition, the influence of drought on nectar production and metabolism in nectaries should be investigated, since very little is currently known about this. The influence of drought stress on nectaries, nectar and leaves of 4 day- and night-flowering Nicotiana species (pollinated by sunbirds, hummingbirds, hawkmoths or bats) were investigated. The nectar volume, as well as metabolite concentrations (sugars, amino acids), inorganic ions and starch were measured. PCA and PERMANOVA were applied to determine the relative importance of different drought conditions on metabolism of nectaries and nectar. Drought stress led to changes in composition of nectaries and nectar in all four Nicotiana species. The day-flowering species had relatively similar changes, whereas the night-flowering species differed from these and also from each other. Quantities of sugars, amino acids and inorganic ions per flower decreased sharply in all Nicotiana species because of a strong decrease in nectar volume. Drought stress not only compromises plant growth but also nectar secretion and composition. These changes are likely to affect plant-pollinator interactions and may negatively impact successful pollination.