Medicinal alkaloids in lotus accumulate in highly specific organs, yet the molecular basis of this spatial pattern has remained unclear. A new study reveals the genetic circuitry that explains why aporphine-type benzylisoquinoline alkaloids (BIAs) accumulate in lotus leaves while bis-BIAs concentrate in plumules. Researchers identified two tandemly duplicated but tissue-specialized enzymes, NnCYP80G and NnCYP80A, whose differential expression drives organ-specific alkaloid biosynthesis. They further uncovered a jasmonate-responsive transcriptional cascade involving NnMYC2 and NnMYB14 that activates these enzymes and coordinates BIA production. This work provides the first mechanistic explanation for organ-specific BIA accumulation in lotus and establishes a regulatory framework for improving medicinal alkaloid yield.
Benzylisoquinoline alkaloids (BIAs) are a diverse class of plant-derived compounds with major pharmacological value, including well-known examples such as morphine and berberine. In lotus (Nelumbo nucifera), BIAs serve as key bioactive constituents and contribute to antioxidant, anticancer, and hepatoprotective properties. Remarkably, different lotus organs accumulate distinct BIA types: aporphines are enriched in leaves, whereas bis-BIAs dominate in plumules. Although candidate biosynthetic enzymes had been proposed, the mechanisms controlling their tissue specificity and regulatory hierarchy remained unresolved. Jasmonate signaling is known to stimulate secondary metabolism, yet how it governs spatial alkaloid biosynthesis in lotus was unknown. Based on these challenges, in-depth investigation into the spatial regulation of lotus alkaloid biosynthesis became necessary.
In a study published (DOI: 10.1093/hr/uhaf283) in 2025 in Horticulture Research , scientists from Wuhan Botanical Garden of the Chinese Academy of Sciences report that organ-specific benzylisoquinoline alkaloid biosynthesis in lotus is governed by a transcriptional cascade involving NnMYC2, NnMYB14, and two tissue-specific cytochrome P450 enzymes, NnCYP80G and NnCYP80A. By integrating genome-wide gene mining, enzyme activity assays, transient overexpression experiments, and promoter-binding analyses, the team uncovered how jasmonate signaling connects environmental cues to spatially controlled alkaloid production.
Through genome-wide analysis of lotus P450 genes, researchers identified six CYP80 candidates, among which NnCYP80G and NnCYP80A displayed striking tissue-specific expression patterns. NnCYP80G was predominantly expressed in laminae, while NnCYP80A accumulated specifically in plumules. The two genes are tandemly arranged on chromosome 2 but possess distinct promoter architectures, suggesting functional divergence following gene duplication.
Functional assays in Nicotiana benthamiana confirmed their catalytic specialization. NnCYP80G efficiently converted (R)-reticuline into corytuberine and (R)-N-methylcoclaurine into glaziovine, revealing both proaporphine and aporphine synthase activities. In contrast, NnCYP80A catalyzed the formation of the bis-BIA nelumboferine. Transient overexpression of NnCYP80A in lotus petals significantly enhanced bis-BIA accumulation, validating its in planta function.
Upstream regulation was traced to the jasmonate pathway. The master regulator NnMYC2 activated expression of the R2R3-MYB transcription factor NnMYB14, which directly bound to promoters of both CYP80 genes. While NnMYB14 strongly induced NnCYP80G and aporphine production, its effect on NnCYP80A was comparatively moderate, helping explain the differential alkaloid accumulation between organs.
"Our findings demonstrate how gene duplication followed by promoter divergence can generate organ-specific metabolic specialization," said the corresponding author. "The NnMYC2–NnMYB14–NnCYP80 module establishes a hierarchical regulatory framework that links jasmonate signaling to spatial control of alkaloid biosynthesis. This not only clarifies long-standing questions about lotus metabolism but also provides valuable targets for metabolic engineering of medicinal compounds."
By uncovering the regulatory logic that partitions distinct alkaloids into specific lotus organs, this study opens new opportunities for pharmaceutical crop improvement. Manipulating the NnMYC2–NnMYB14 cascade or engineering CYP80 promoter elements could enhance production of desired aporphines or bis-BIAs in targeted tissues. The work also illustrates how tandem gene duplication can drive metabolic innovation through spatial specialization. Beyond lotus, the regulatory model may inform synthetic biology strategies aimed at reconstructing alkaloid pathways in heterologous systems, advancing sustainable and scalable production of high-value medicinal compounds.
