Abstract
Plants have evolved strategies to maintain photosynthesis and mitigate tissue-damaging high light. In some dioecious seed plants, these strategies are sexually dimorphic and are linked to spatial segregation of the sexes (SSS) along light gradients. In vascular tissue-free plants (bryophytes) with separate sexes, SSS is common, but how light gradients, sexual dimorphisms, and SSS correlate is not well understood. To test if sexual dimorphisms in vegetative or sexual stages lead to light-associated SSS in bryophytes, we used Marchantia inflexa whose males occupy a wider range of light conditions, including higher light conditions, than females. We also tested if changes in development differed between sexes. We grew 25 males and 25 females in a glasshouse with clones in low and high light and assessed pigment and biomass allocation traits in vegetative and sexual thalli (analogous to leaves), representing non-sexual and sexually reproductive stages. We expected males to exhibit traits consistent with high light acclimation more than females and greater sex differences in sexual thalli due to specialization. Further, we reasoned that males would change more between stages than females. For sexual thalli, males had higher carotenoid/chlorophyll ratios (consistent with expectation), while females had higher chlorophyll a/b ratios and dry matter content (opposite from expectations). Vegetative thalli were not sexually dimorphic but were more plastic to light than sexual thalli. Overall, the stages differed more for males than females, but without regard for light. However, female stages differed more for dry matter content. Males generally need greater change in pigmentation and biomass allocation than females between stages, and we posit links for individual traits to sex function. Specialization in sexual thalli constrains their plasticity to light compared to vegetative thalli. Yet, neither sexual dimorphism in sexual thalli nor greater change between stages for males than females clearly leads to light-associated SSS.
| Original language | English |
|---|---|
| Article number | plaf010 |
| Journal | AoB PLANTS |
| Volume | 17 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2025 |
Bibliographical note
Publisher Copyright:© 2025 The Author(s).
Funding
We thank Phil Bonner for the use of a spectrophotometer, Ian Stewart for assistance in assessing acetate filter absorbance, Kristen Hillegass for allowing us to use her photograph of Marchantia inflexa in the field (Fig. 1a), and Hansika Herath for assistance with arranging figures. We thank the Wildlife Section of the Forestry Division of the Republic of Trinidad and Tobago for collection and export permits, and the Water and Sewage Authority for access to the Quare and North Oropuche locations. We are also grateful for statistical assistance from Eric Roemmele and helpful comments from Associate Editor Shan Kothari and two anonymous reviewers. Conflict of interest: None. This work was supported by a Gertrude Flora Ribble research scholar award to J.D.M. from the Biology Department, University of Kentucky
| Funders | Funder number |
|---|---|
| Hansika Herath | |
| Forestry Division of the Republic of Trinidad and Tobago | |
| University of Kentucky |
Keywords
- carotenoids
- chlorophyll
- developmental stage
- dry matter content
- Marchantia inflexa
- pigments
- plasticity
- sexual dimorphism
- specific leaf area
ASJC Scopus subject areas
- Plant Science