Proof of anthocyanins in the carnivorous plant genus Nepenthes

Abstract

Yellow to red colored betalains are a chemotaxonomic feature of Caryophyllales, while in most other plant taxa, anthocyanins are responsible for these colors. The carnivorous plant family Nepenthaceae belongs to Caryophyllales; here, red-pigmented tissues seem to attract insect prey. Strikingly, the chemical nature of red color in Nepenthes has never been elucidated. Although belonging to Caryophyllales, in Nepenthes, some molecular evidence supports the presence of anthocyanins rather than betalains. However, there was previously no direct chemical proof of this. Using UHPLC-ESI-HRMS, we identified cyanidin glycosides in Nepenthes species and tissues. Further, we reveal the existence of a complete set of constitutively expressed anthocyanin biosynthetic genes in Nepenthes.Thus, here we finally conclude the long-term open question regarding red pigmentation in Nepenthaceae.

Distribution of Acetogenic Naphthoquinones in Droseraceae and Their Chemotaxonomic Utility

“…Structurally and biosynthetically similar anthraquinones (e.g., emodin) are known from Polygonaceae within the same order [5]. Apart from genetic evidence, these characteristic metabolites clearly support the separation of Nepenthales from the sister order Caryophyllales (sensu stricto), which is in turn characterized by the common presence of betalains [6] that are lacking in Nepenthales [7,8]. Another noteworthy coincidence is the presence of at least six genera of carnivorous plants in four families of Nepenthales (Nepenthes of Nepenthaceae, Dionaea, Aldrovanda and Drosera of Droseraceae, Drosophyllum of Drosophyllaceae, Triphyophyllum of Dioncophyllaceae; carnivory is monophyletic in Nepenthales and became lost at least twice in this lineage, in two out of the three genera of Dioncophyllaceae and in all Ancistrocladaceae), while no carnivorous members of Caryophyllales are known [9].…”

Morphology and pitcher's color Nepenthes in Batu Lubang Sibolga Area, North Sumatra Province, Indonesia

“…That is because the role of the upper pitcher with a brighter color tends to carry out photosynthesis rather than attract prey. Furthermore, the tendrils' role in photosynthesis is because it grows as of the leaf's mid-bone, where the leaves are tasked with photosynthesis (Dávila-Lara et al 2021). In addition, the position of the Nepenthes' upper pitcher is directly exposed to sunlight.…”

“…The formation of anthocyanins in the pitcher, including the body of the pitcher, is not yet known with certainty whether its function is to attract prey or only as an adaptation of plants that grow in nitrogen-deficient soil; this still requires further research (Brearley 2021;Dávila-Lara et al 2021;Gaume et al 2016). According to Yang et al (2022) and Albert et al (2015) the formation of anthocyanins in leaves is closely related to plant lack of N and P elements.…”

Prey composition of six Nepenthes species in Pematang Gadung, West Kalimantan

“…Anthocyanins in the pitcher provide signals to attract insects to visit the pitchers [29]. In addition to the color, the scent of nectar from the pitcher is also an attractant for various prey to visit the pitcher [30]. The scent derived from the nectar found in the peristome effectively attracts insects; the nectar makes the peristome area slippery and caused the insects to slip and fall into the pitcher [31].…”