Liverworts depend on water for fertilization, but their spores disperse more effectively in drier conditions. A study of Marchantia polymorpha suggests its female reproductive structures evolved through successive changes that addressed these competing demands.
The research, published in Nature Plants and led by Xu Bo of the Institute of Botany of the Chinese Academy of Sciences, identified a previously unknown system that moves water upward against gravity. Specialized surface structures on the female reproductive stalk and receptacle work together to deliver water to elevated reproductive organs, helping fertilization. Their coordinated development is regulated by MpLAS, a transcription factor from the GRAS family.
The team also found that another GRAS-family protein, MpGRAS10, helps form the reproductive stalk. It promotes the expression of the gibberellin biosynthesis genes MpKAOL1 and MpKAOL2, contributing to the development of elevated structures that can aid spore dispersal.
Comparative evolutionary analyses indicate that the stalk appeared before the specialized surface structures involved in water delivery. The findings support a stepwise account: an early change favored spore dispersal, while later adaptations helped address the resulting challenge of delivering water for fertilization.
The researchers say the work shows how contrasting functional demands can shape the sequential evolution of complex structures. They also suggest that the water-transport findings may inform research into passive, directional liquid-transport systems in bioinspired engineering.
The study, by Xiaotong Qi and colleagues, is titled “Directional water transport system resolves fertilization–dispersal conflicts in Marchantia” and was published in Nature Plants (2026).
Sources: Phys.org.