In planta high levels of hydrolysable tannins inhibit peroxidase mediated anthocyanin degradation and maintain abaxially red leaves of Excoecaria Cochinchinensis

Abstract

Background Abaxially anthocyanic leaves of deeply-shaded understorey plants play important ecological significance for the environmental adaption. In contrast to the transient pigmentation in other plants, anthocyanins are permanently presented in these abaxially red leaves, however, the mechanism for the pigment maintenance remains unclear. In the present study, we investigated phenolic metabolites that may affect pigment stability and degradation in Excoecaria cochinchinensis (a bush of permanently abaxial-red leaves), via a comparison with Osmanthus fragrans (a bush of transiently red leaves). Results High levels of galloylated anthocyanins were identified in the Excoecaria but not in the Osmanthus plants. The galloylated anthocyanin showed slightly higher stability than two non-galloylated anthocyanins, while all the 3 pigments were rapidly degraded by peroxidase (POD) in vitro. High levels of hydrolysable tannins [mainly galloylglucoses/ellagitannins (GGs/ETs)] were identified in Excoecaria but none in Osmanthus . GGs/ETs showed inhibition effect on POD, with IC50 ranged from 35.55 to 83.27 μM, correlated to the markedly lower POD activities detected in Excoecaria than in Osmanthus . Strong copigmentation was observed for GGs/ETs and anthocyanins, with more than 30% increase in the red intensity of non-galloylated anthocyanin solutions. In the leaf tissue, the hydrolysable tannins were observed to be co-localized with anthocyanins at the abaxial layer of the Excoecaria leaves, correlated to the low POD activity, more acidity and increased red intensity of the tissue. Conclusion The results suggest that the Excoecaria leaves accumulate a distinct group of phenolic metabolites, mainly GGs/ETs, at the abaxial layer, which prevent anthocyanin degradation and increase the pigment stability, and consequently lead to the permanent maintenance of the red leaves. Electronic supplementary material The online version of this article (10.1186/s12870-019-1903-y) contains supplementary material, which is available to authorized users.

Transcriptome analysis of flower color reveals the correlation between SNP and differential expression genes in Phalaenopsis

“…SGTase can be used as a multiple phenylpropanoid glucosylation enzyme, which exhibited signi cant activity with avonoids [35].β-glucosidase (bglx) was an anthocyanase, which can hydrolyze anthocyanidins into anthocyanin [33]. E1.11.1.7 is a peroxidase that may lead to the degradation of anthocyanin [36]. Above previous studies further con rmed the rationality and reliability of identi ed genes in phalaenopsis from RNA-seq in this study.…”

Extracts of Digested Berries Increase the Survival of Saccharomyces cerevisiae during H2O2 Induced Oxidative Stress

“…They showed that in human cells the phenolic propyl gallate, synthesized by the condensation of gallic acid and propanol, might, in certain conditions, increase the levels of reactive oxygen species (ROS) and/or promote depletion of protective enzymes or glutathione. Moreover, high (poly)phenol levels can inhibit enzymes such as peroxidases and catalases [ 40 , 41 ]. It is also well known that (poly)phenols from berries can exhibit antimicrobial activity [ 42 ].…”

Why Are There so Many Plant Species That Transiently Flush Young Leaves Red in the Tropics?

“…It is therefore not surprising that both have a relatively higher accumulation within red young leaves in the present research. Recent literature suggests that high levels of hydrolysable tannins [mainly galloylglucoses/ellagitannins (GGs/ETs)] in the young leaves of plants can inhibit POD mediated anthocyanin degradation and can increase stability and color intensity of anthocyanins by copigmentation activity (Luo et al, 2019). Previous studies have also reported that the delayed greening strategy is widespread in the tropics (Coley and Kursor, 1996;Dominy et al, 2002), and that young tropical leaves with visually striking red coloration have a greater increase in chemical defenses compared with mature leaves than do their temperate counterparts (Coley and Aide, 1989).…”