New method reveals pollen's UV resistance linked to sporopollenin chemistry

By analyzing the autofluorescence intensity of sporopollenin in the pollen wall, researchers have identified a significant link between UV absorption and environmental radiation levels.

Land plants, especially spores and pollen, face numerous environmental stressors, including harmful UV-B radiation. As sessile organisms, they are exposed to UV without the protective buffer of water, making their survival dependent on efficient UV defense mechanisms. Sporopollenin, a robust polymer found in the outer layer of pollen and spores, has been identified as a key player in absorbing UV radiation, preventing damage to the delicate DNA within these reproductive units. However, variations in sporopollenin chemistry across plant species have made it challenging to establish a universal marker for UV resistance. Existing research has focused on specific compounds like para-coumaric acid (p-CA) and ferulic acid (FA), which are known to absorb UV radiation. Yet, no single marker has universally linked sporopollenin chemistry to UV resistance across different plant species.

A study (DOI: 10.48130/seedbio-0025-0016 ) published in Seed Biology on 10 October 2025 by Ying Xiao’s & Jing-Shi Xue’s team, Shanghai University of Traditional Chinese Medicine & Shanghai Normal University, offers new insights into how plants adapt to UV stress, with potential applications in plant evolution and environmental adaptation studies.

The research focused on quantifying the Integral of Sporopollenin Autofluorescence Intensity (ISAI) in pollen and spores using Laser Scanning Confocal Microscopy (LSCM). This method measures the autofluorescence emitted by the pollen wall when exposed to UV radiation, reflecting its capacity to convert harmful short-wave UV radiation into less damaging long-wave visible light. The researchers analyzed pollen from 55 plant species, including 18 Arabidopsis thaliana ecotypes, and found that ISAI values varied significantly depending on the ecological exposure to solar irradiance. Plants in high-radiation environments, such as seed plants exposed to direct sunlight, exhibited higher ISAI values compared to those in shaded habitats, like pteridophytes and bryophytes. This correlation indicates that ISAI can serve as a reliable indicator of UV resistance, with species flowering during high solar radiation seasons showing particularly elevated ISAI levels. Further analysis of Arabidopsis thaliana ecotypes demonstrated that ISAI is heritable, with a negative correlation between ISAI values and pollen germination decline under UV-B treatment. Genetic analysis showed that phenylpropanoid phenolics, including para-coumaric acid and ferulic acid, are essential components of sporopollenin responsible for the observed ISAI variations, confirming their role in UV-B protection. These findings highlight the importance of sporopollenin chemistry in pollen UV resistance and propose ISAI as a novel metric for studying plant adaptation to UV environments.

The ISAI method provides a non-destructive, efficient way to assess pollen UV resistance, a critical factor for plant reproductive success. This tool is especially useful for studying the effects of environmental factors on plant adaptation, offering a new approach to exploring how plants evolve to cope with changing UV radiation levels. By linking sporopollenin autofluorescence to UV resistance, ISAI could also be applied in ecological and evolutionary research, offering insights into plant responses to climate change and UV stress.

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References

DOI

10.48130/seedbio-0025-0016

Original Source URL

https://doi.org/10.48130/seedbio-0025-0016

Funding information

This work was supported by grants from the National Natural Science Foundation of China (31900165), Shanghai Municipal Education Commission (2019-01-07-00-02-E00006), Science and Technology Commission of Shanghai Municipality (17DZ2252700, 18DZ2260500, and 21DZ2202300), and the Postdoctoral Fellowship Program (Grade C) of China Postdoctoral Science Foundation (GZC20231699). We would like to thank Dr. Zong-Xin Ren (Kunming Institute of Botany, Chinese Academy of Sciences) for the helpful comments on the manuscript.

About Seed Biology

Seed Biology (e-ISSN 2834-5495) is published by Maximum Academic Press in partnership with Yazhou Bay Seed Laboratory. Seed Biology is an open access, online-only journal focusing on research related to all aspects of the biology of seeds, including but not limited to: evolution of seeds; developmental processes including sporogenesis and gametogenesis, pollination and fertilization; apomixis and artificial seed technologies; regulation and manipulation of seed yield; nutrition and health-related quality of the endosperm, cotyledons, and the seed coat; seed dormancy and germination; seed interactions with the biotic and abiotic environment; and roles of seeds in fruit development. Seed biology publishes a wide range of research approaches, such as omics, genetics, biotechnology, genome editing, cellular and molecular biology, physiology, and environmental biology. Seed Biology publishes high-quality original research, reviews, perspectives, and opinions in open access mode, promoting fast submission, review, and dissemination freely to the global research community.