Photosynthetic activity in the heterotrophic plant genus <i>Cuscuta</i> (Convolvulaceae) is modulated by phylogeny and ontogeny
Bibliographic record
Abstract
BACKGROUND AND AIMS: Photosynthesis is central to plant function, yet it has been repeatedly lost or diminished in parasitic angiosperm lineages. This variation raises questions about how photosynthetic function is retained, modified or repurposed in the evolutionary context of parasitism. Cuscuta species, as a model system for studying parasitism, exhibit varying degrees of plastid functionality and photosynthetic ability, based on genomic and ultrastructure studies. However, few direct physiological studies exist, and none that span multiple developmental stages of autotrophic, mixotrophic and non-photosynthetic species in a phylogenetic framework. METHODS: To address this gap, we paired photosynthetic activity measurements from fluorometry with quantitative analysis of chlorophylls and carotenoids from multiple developmental stages in 14 Cuscuta species, representing the phylogenetic breadth of the genus, and a closely related autotrophic species. Multivariate data were analysed using non-parametric hypothesis tests, and comparative phylogenetic patterns were explored through Bayesian model testing. KEY RESULTS: Photosynthetic activity and chlorophyll and carotenoid content were highest in meristematic regions (e.g. shoot tips and developing seeds) and lowest in older stems or haustoria. Neoxanthin, a carotenoid typically highly conserved in plants, appears to have been lost once in Cuscuta and subsequently re-gained in certain lineages. Complex relationships between photosynthetic activity and lutein epoxide concentration suggest differing roles in developmental stages with high and low energetic needs. CONCLUSIONS: These findings provide substantial evidence that photosynthesis in Cuscuta is not vestigial but rather modulated based on developmental stage and across phylogenetic history, revealing a dynamic interplay between parasitism and photosynthetic function.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".