Not all anthocyanins are born equal: distinct patterns induced by stress in Arabidopsis

Abstract

Main ConclusionDifferent abiotic stress conditions induce distinct sets of anthocyanins, indicating that anthocyanins have different biological functions, or that decoration patterns of each anthocyanin are used for unique purposes during stress.The induction of anthocyanin accumulation in vegetative tissues is often considered to be a response of plants to biotic or abiotic stress conditions. Arabidopsis thaliana (Arabidopsis) accumulates over 20 anthocyanins derived from the anthocyanidin cyanidin in an organ-specific manner during development, but the anthocyanin chemical diversity for their alleged stress protective functions remains unclear. We show here that, when grown in various abiotic stress conditions, Arabidopsis not only often accumulates significantly higher levels of total anthocyanins, but different stress conditions also favor the accumulation of different sets of anthocyanins. For example, the anthocyanin patterns of seedlings grown at pH 3.3 or in media lacking phosphate are very similar and characterized by relatively high levels of the anthocyanins A8 and A11. In contrast, anthocyanin inductive conditions (AIC) provided by high sucrose media are characterized by high accumulation of A9* and A5 relative to other stress conditions. The modifications present in each condition correlate reasonably well with the induction of the respective anthocyanin modification enzymes. Taken together, our results suggest that Arabidopsis anthocyanin profiles provide ‘fingerprints’ that reflect the stress status of the plants.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-014-2079-1) contains supplementary material, which is available to authorized users.

Abiotic stresses induce different localizations of anthocyanins in Arabidopsis

“…Anthocyanins are commonly induced in plant vegetative tissues in response to a number of different abiotic stresses including drought, salinity, excess light, sub-or supra-optimal temperatures, and nitrogen and phosphorous deficiency. [2][3][4][5][6][7][8] The proposed roles of anthocyanins during abiotic stresses include quenching of ROS, 9,10 photoprotection, 11,12 stress signaling, 13,14 and xenohormesis (i.e., the biological principle that relates bioactive compounds in environmentally stressed plants and the increase in stress resistance and survival in animals that feed from them). 15,16 Plants as a group produce hundreds of structurally distinct anthocyanin species.…”

“…4 We analyzed seedlings grown in 8 abiotic stress conditions, including high salinity, cold, and an artificial stress medium termed anthocyanin induction condition (AIC), which consists of 3% sucrose and no additional nutrients. The fact that distinct profiles of anthocyanins are induced by different abiotic stresses suggested that different anthocyanins, or profiles of anthocyanins, have different functions in planta.…”

“…17 The anthocyanin profile induced by drought 17 was most similar to that induced in response to salt (MgSO 4 ) stress in our experiments. 4 Therefore, it is possible that plants exposed to drought and salt stresses take advantage of the same anthocyanin, or set of anthocyanins, whereas plants subjected to other abiotic stress conditions may benefit from different anthocyanin species.…”

“…A11 was the major anthocyanin induced in Arabidopsis in response to salt (MgSO 4 ) 4 and drought 17 stresses. The synthesis of A11 is metabolically more costly than C3G, an anthocyanin that has widespread occurrence in plant species, as A11 has 6 additional sugar and acyl decorations, and has 3 times the mass of C3G.…”

“…4 To determine whether the localization of anthocyanins in leaves differ between oxidative or non-oxidative stress growth conditions, we analyzed seedlings grown in high salt and high light (100 mM MgSO 4 , 150 mmol m 2 s ¡1 ) and AIC, respectively. In cotyledons grown in AIC, anthocyanins accumulated mainly in the abaxial epidermis and vasculature, but not in mesophyll cells (Fig.…”