Complex pigment evolution in the Caryophyllales

Abstract

SummaryCarotenoids and flavonoids including anthocyanins are the predominant pigments in flowering plants, where they play important roles in pollination, seed dispersal, protection against stress and signalling. In certain families within the Pentapetalae order Caryophyllales, an unusual class of pigments, known as betalains, replaces the more common anthocyanins. This isolated occurrence of betalains in the Caryophyllales has stimulated over half a century of debate and experimentation. Numerous hypotheses have been suggested to explain the phylogenetically restricted occurrence of betalains and their apparent mutual exclusion with anthocyanins. In this review, we evaluate these hypotheses in the face of a changing interpretation of Caryophyllales phylogeny and new comparative genetic data. Phylogenetic analyses expose substantial gaps in our knowledge of the early evolution of pigments in the Caryophyllales and suggest pigmentation to be much more labile than previously recognized. Reconstructions of character evolution imply multiple switches from betalain to anthocyanin pigmentation, but also allow for possible multiple origins of betalains. Comparative genetic studies propose possible mechanisms underlying switches between pigment types and suggest that transcriptional down-regulation of late-acting enzymes is responsible for a loss of anthocyanins. Given these insights from molecular phylogenetics and comparative genetics, we discuss outstanding questions and define key goals for future research.

Salicylic acid on antioxidant activity and betacyan in production from leaves of Alternanthera tenella

“…Betalains and anthocyanins (fl avonoids) are two different chemical classes of pigments and are never found together in the same plant (GANDÍA-HERRERO et al, 2005). Such exclusiveness may have an explanation at the biochemical level -the relevant enzymes for the production of anthocyanins are not certainly expressed in betalain-producing plants (BROCKINGTON et al, 2011).…”

Techno-commercial Aspects of Relevance to Red Beet

“…Phylogenetic insights have indicated that betalains appear to have evolved at least twice: once within a fungal lineage, the Basidiomycetes (e.g., Amanita muscaria ), and once among fl owering plants of the order Caryophyllales, where they replace the otherwise ubiquitous anthocyanins (Brockington et al 2011 ). The fact that betalains originated much later in evolution and exist by mutual replacement of anthocyanins indicate that these plants might have chosen to switch over to betalains because of the wide spectrum of permutations and combinations of colors offered by making small adjustments in the biosynthetic pathway after betalamic acid synthesis and because the pigments are stable through a wide pH range.…”

Generic relationships among Molluginaceae inferred from a molecular phylogenetic analysis of the matK gene

“…Several genera previously treated under the family Molluginaceae have therefore been shifted to other families. For example, the genus Corbichonia is now in the family Lophiocarpaceae, Limeum in Limeaceae, and Corrigiola with Telephium are in Caryophyllaceae (Endress and Bittrich, 1993;Cuénoud et al, 2002;Arakaki et al, 2011;Brockington et al, 2011;Christin et al, 2011;Christenhusz et al, 2014). As per the taxonomic treatment of Angiosperm Phylogeny Group (2009), the family Molluginaceae comprises ca.…”