Biology subjects

Cardenas, P. D.

Publications and source records attributed to Cardenas, P. D..

4 recordsLinked to original sources

bioRxiv2026

Glycosylation-dependent Turnover of Triterpenoid Saponins Controls Insect Deterrence

Background and AimsPlants deploy triterpenoid saponins as chemical defences against herbivores, yet it remains unclear whether insect digestion detoxifies these compounds or generates equally or more active metabolites. Because saponin bioactivity depends strongly on glycosylation patterns, we examined the fate and defensive activity of hederagenin-derived saponins during herbivory. MethodsLarvae of Plutella xylostella were fed leaf discs containing structurally defined hederagenin-derived saponins. Saponin composition in treated leaves and larval frass was analysed by LC- qTOF-ESI-MS/MS. Feeding assays were used to compare the antifeedant activity of mono- and bidesmosidic forms. Key ResultsLarvae selectively metabolized complex hederagenin-derived saponins into simpler forms, with cellobiosides converted into monoglucosides during digestion, resulting in a marked shift in saponin composition between ingested material and frass. Feeding assays showed that monodesmosidic saponins strongly deterrer feeding, whereas bidesmosidic saponins were largely inactive. The loss of activity in bidesmosidic saponins was not explained by differential metabolism, indicating that glycosylation patterns directly determine biological function. ConclusionsInsect herbivores selectively modify saponin structures through deglycosylation, thereby altering their defensive properties. Our findings demonstrate that glycosylation governs both saponin activity and metabolic fate, highlighting insect-driven turnover as a critical component of plant chemical defence during plant-herbivore interactions. Issue SectionOriginal article

biochemistry↗

bioRxiv2026

Phylogenomics reveals reticulate evolution in the Chenopodium album complex

Background and AimsComplex genomic histories driven by hybridization and polyploidy can shape key plant traits such as defense, stress tolerance, and toxicity, particularly in Amaran-thaceae, which includes crops such as quinoa and spinach. Within this family, white goosefoot (Chenopodium album) is both a widespread agricultural weed and a traditional food resource. However, its evolutionary history is complicated by discordant signals among genomic markers within the C. album complex, comprising diploid, tetraploid, and hexaploid taxa. Here, we tested whether reticulate evolution underlies this genome-wide discordance. MethodsUsing genome-scale phylogenomic data, we analysed 2,298 conserved nuclear loci (BUSCO genes) across 27 Amaranthaceae genomes. Both single- and multicopy gene families were included to capture signals of gene duplication, incomplete lineage sorting, and hybridization. Complementary phylogenomic approaches were used to evaluate whether the evolutionary history is best supported by strictly bifurcating relationships or by reticulate evolution. Key ResultsA consistent C. album lineage was recovered, comprising tetraploid and hexaploid C. album cytotypes together with C. suecicum, C. strictum, C. formosanum, C. acuminatum, and C. opulifolium. Phylogenetic discordance was concentrated within Chenopodium, particularly around the C. album and C. quinoa lineages. Models incorporating hybridization fit better than strictly bifurcating relationships, supporting at least two reticulation events. Hybridization signals were detected in 271 loci in tetraploid and 270 in hexaploid C. album, of which 232 were shared, indicating a shared hybrid origin rather than independent lineages. ConclusionsThe evolutionary history of the C. album lineage is best explained by reticulate processes involving hybridization and polyploidy. Conserved nuclear loci retain persistent signatures of these events, helping to resolve complex evolutionary histories in polyploid plant systems.

plant biology↗

bioRxiv2026

A genomic and functional framework for the rapid domestication of the wild plant Chenopodium album

Global reliance on a small number of genetically uniform crops makes our food system increasingly vulnerable to pests, diseases, and climate change, highlighting the need to develop resilient local species as crops. Chenopodium album, a stress-tolerant, protein-rich wild plant whose seeds were part of prehistoric Northern European diets and whose leaves are still foraged worldwide, remains undomesticated despite its agrifood potential. We established a Danish collection of 143 accessions and combined seed metabolomics, ploidy assessment and genomics to uncover the molecular basis of key nutritional and anti-nutritional traits. Seed profiling revealed substantial variation in protein content (14-22%), comparable to or higher than major crops, and 16 distinct triterpenoid saponins, which are widespread bitter and anti-nutritional compounds. Seed production of field-grown lines reached up to 1.5 t/ha in trials conducted in Denmark, demonstrating promising yield potential. A high-quality tetraploid genome of a low-saponin line was assembled and contrasted with resequencing of a diploid high-saponin line in order to uncover the genetic basis of saponin variation in C. album. Comparative genomic, phylogenetic, and transcriptomic analyses identified structural variants and candidate genes associated with saponin biosynthesis, and functional validation confirmed the coordinated activity of a {beta}-amyrin synthase, three CYP716 cytochromes P450, and a glucuronosyltransferase that reconstitute the core C. album saponin pathway. Together, these results define the genomic and biochemical foundation of C. album, establishing a platform for its rapid domestication as a locally adapted, high-protein seed crop and a model for translating wild plant diversity into future food security.

plant biology↗

bioRxiv2025

Metabolic engineering of Barbarea vulgaris identifies β-amyrin synthase LUP5 as a determinant of saponin-mediated insect resistance

Plant-insect coevolution has been a major driver of specialized metabolite diversification, yet the genetic basis of natural variation in defensive chemistry remains poorly understood. The wild crucifer Barbarea vulgaris comprises two ecotypes, an insect-resistant G-type and a susceptible P-type, characterized by distinct triterpenoid saponin profiles. To investigate the causal relationship between saponin composition and insect resistance, we established a stable transformation system for B. vulgaris. Expression of the G-type {beta}-amyrin synthase gene LUP5 in the susceptible P-type conferred up to a 95% reduction in Plutella xylostella feeding, accompanied by increased accumulation of three hederagenin-derived monodesmosidic saponins. Comparison of LUP5 expression driven by its native promoter and by the constitutive 35S promoter revealed that the native promoter leads to increased hederagenin accumulation and is activated later in development, which may prevent early metabolic stress and allow coordinated expression of downstream pathway genes. In contrast, silencing of CYP72A552 by RNAi decreased total hederagenin levels by approximately 40% without affecting resistance, indicating threshold-dependent defense. Our results provide direct in planta evidence that LUP5 is a key determinant of natural variation in insect resistance in B. vulgaris, underscoring the pivotal role of the saponin backbone in herbivore deterrence. By linking promoter activity to metabolite structural diversity, this work provides mechanistic and conceptual insight into how plants coordinate specialized metabolism and defense.

plant biology↗