Anthocyanin biosynthesis is controlled by structural enzymes and transcription factors, especially MYB regulators that activate or repress pigment production. Ethylene’s role differs widely among plant species, sometimes promoting and sometimes inhibiting pigmentation. In lilies, the underlying mechanism has remained unclear, particularly because Asiatic lilies show ethylene-induced inhibition, while 'Viviana' lilies respond with strong activation. Regulatory components including MYB activators, MYB repressors, and ERF proteins have been implicated, but their interactions were unknown. Based on these challenges, deeper investigation into the ethylene-regulated transcriptional network is required to clarify how pigment accumulation is achieved in lilies.
Researchers from Shenyang Agricultural University and collaborators reported (DOI: 10.1093/hr/uhaf059) on June 1, 2025, in Horticulture Research that ethylene enhances pigmentation in 'Viviana' lily by activating a regulatory cascade involving LvMYB5, LvERF113, and LvMYB1. Using transcriptomics, gene silencing, transient expression, protein–protein interaction assays, and promoter analyses, the team uncovered an unusual mechanism in which LvERF113, though a repressor-type ERF, promotes anthocyanin synthesis by counteracting LvMYB1. This discovery explains why ethylene triggers strong coloration in 'Viviana' lilies but not in other lily types.
The researchers first confirmed that ethylene significantly increases anthocyanin levels in tepals, while 1-MCP suppresses pigmentation. Transcript analysis identified LvERF113 as an ethylene-responsive ERF strongly induced during pigmentation. Functional assays showed that silencing LvERF113 reduces pigment levels and downregulates structural genes, whereas overexpression enhances them. Although LvERF113 contains an EAR repression motif, it promotes anthocyanin accumulation by inhibiting LvMYB1 both transcriptionally and post-translationally. Promoter assays demonstrated that the activator LvMYB5 directly binds the LvERF113 promoter and induces its transcription. In turn, LvERF113 binds the GCC-box in the LvMYB1 promoter to repress LvMYB1 expression. Protein-interaction assays (Y2H, BiFC, pull-down, luciferase complementation) further showed that LvERF113 physically interacts with LvMYB1, neutralizing its inhibitory action on structural genes such as LvCHS, LvF3H, LvDFR, LvANS, and LvUFGT.
These interactions form the LvMYB5–LvERF113–LvMYB1 module, which channels ethylene signals into enhanced anthocyanin biosynthesis. This mechanism differs sharply from Asiatic lilies, where ethylene suppresses pigmentation, revealing species-specific transcriptional wiring underlying flower coloration.
“This study offers an elegant explanation for how ethylene can enhance pigmentation in certain lily varieties,” said a senior plant molecular biology expert not involved in the study. “The discovery that LvERF113, a classical repressor-type ERF, can promote anthocyanin synthesis by inhibiting another repressor represents a significant shift in our understanding of transcriptional logic in ornamental plants. This dual-inhibition mechanism provides a fresh framework for interpreting hormone-driven color development and opens new avenues for manipulating floral traits with precision.”
The findings provide a molecular framework for manipulating color intensity in ornamental lilies. Targeting nodes within the LvMYB5–LvERF113–LvMYB1 module may enable breeders to develop cultivars with enhanced, stable, or customized pigmentation. The results also offer guidance for applying ethylene derivatives to regulate coloration during production, shipping, and postharvest handling. More broadly, the study illustrates how inhibitor-of-inhibitor regulatory designs can be leveraged to fine-tune metabolic pathways, offering applications for pigment engineering and stress-responsive traits across horticultural crops.
###
References
DOI
10.1093/hr/uhaf059
Original Source URL
https://doi.org/10.1093/hr/uhaf059
Funding information
This work was financially supported by Funds for the China Agriculture Research System (CARS-23) and National Key R&D Program of China (Grant No. 2019YFD1001002).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.