The flying spider monkey tree fern, Alsophila spinulosa, is an ancient vascular plant that has fascinated scientists and plant enthusiasts alike for decades. This unique fern is known for its arborescent habit, large genome, and abundance of bioactive natural products. The recent publication of the A. spinulosa genome in Nature Plants has provided unprecedented insights into the evolution, development, and biochemistry of this charismatic plant.
An overview of Alsophila spinulosa
A. spinulosa also known as the flying spider monkey tree fern is a species in the Cyatheaceae family of tree ferns. It is native to humid forests across Asia, including China, Nepal, India, Myanmar, and Japan. The fern gets its common name from its tall, tree-like growth habit and the two to three meter long fronds that give it a monkey-like appearance.
Some key features that distinguish A. spinulosa include
- A thick woody trunk that can grow over 5 meters tall
- Persistent, spiny stipes that are purplish near the base
- Large, triangular, three-parted fronds
- Prominent round sori on the underside of fronds where spores are produced
- A “skirt” of dead fronds around the top of the trunk
A. spinulosa is valued both ornamentally for its imposing appearance, as well as medicinally. Extracts from the leaves and stems have shown antimicrobial, antioxidant, and antitumor properties. However, overexploitation combined with habitat loss poses a serious threat to wild populations.
The A. spinulosa genome project
To elucidate the evolution and biochemistry of this important fern, researchers sequenced and assembled the giant A. spinulosa genome. At 6.23 Gb, it is one of the largest fern genomes sequenced to date.
The project used a combination of long-read PacBio sequencing, short-read Illumina sequencing, and Hi-C scaffolding to assemble the genome into 69 pseudochromosomes. In total, 67,831 high-confidence protein-coding genes were annotated.
Analysis of the huge genome revealed several interesting findings about genome evolution in ferns:
- Two whole genome duplication events were detected – one ~100 million years ago and one deeper in evolutionary time
- Remarkably high synteny, or conservation of gene order, was observed between chromosomes despite the ancient polyploidy
- The genome showed signatures of decelerated evolution both in terms of nucleotide substitution rates and lack of diploidization following WGD
These results suggest the A. spinulosa genome preserves an ancestral chromosome structure more than other plant genomes studied to date. Researchers proposed its arborescent habit may be linked to this slow rate of genomic evolution.
Insights into vascular development
One of the main goals of sequencing A. spinulosa was to understand vascular development in its tall woody trunk. Detailed anatomical studies found tracheids thickened with lignin are arranged in vascular bundles to provide both structural support and water transport.
Chemical analysis determined guaiacyl (G) lignin is the predominant lignin subunit deposited in tracheid secondary cell walls. Conserved vascular development genes, like NAC and VND transcription factors, were highly expressed in xylem tissue. This implicates their importance in tracheid formation.
Furthermore, over 988 genes were differentially expressed in xylem compared to other tissues. These provide a pool of candidate regulators and biosynthetic genes responsible for A. spinulosa’s distinctive wood.
Discovery of novel natural products
A. spinulosa and other tree ferns are a rich source of bioactive secondary metabolites. Genome sequencing enabled researchers to link genomic features to this expanded metabolic diversity.
Phytochemical analysis of A. spinulosa identified abundant phenylpropanoids, flavonoids, and other compounds. A novel compound named alsophilin was structurally characterized as a dimer of the phenolics piceatannol and hispidin – representing convergence of the stilbene and styrylpyrone pathways.
The A. spinulosa genome contains expanded gene families related to secondary metabolism compared to other ferns. These include more cytochrome P450s, oxidases, and type III polyketide synthases that drive its unique biochemistry.
Demographic history provides conservation insights
Population genomics analysis revealed intriguing aspects of A. spinulosa evolutionary history. Whole genome resequencing of 107 individuals uncovered two major population bottlenecks in the past ~2 million years.
Yunnan province in China harbored the highest genetic diversity, indicating it may be a geographic center of origin. These results provide valuable insight on populations to prioritize for future conservation efforts.
Looking forward
The high-quality A. spinulosa genome fills an important evolutionary gap in plant genomics resources. Ongoing studies will further illuminate our understanding of tree fern biology.
With this critical reference now available, researchers have an invaluable toolkit to explore outstanding questions on topics like:
- The link between arborescence, polyploidy, and genomic conservation
- Developmental control of vascular tissues
- Enzymes involved in natural product biosynthesis
- Demographic modeling to preserve genetic diversity
Unlocking the secrets hidden in the giant fern genome will continue to reveal fascinating insights into plant evolution and biochemistry. The flying spider monkey tree fern still has many mysteries yet to be discovered.
Tree fern (Alsophila spinulosa): Characteristics, Distribution & Habitat, Status and Uses
FAQ
Do tree ferns like sun or shade?
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Partial Shade is Ideal:Most tree ferns, particularly Dicksonia species, do well in areas that receive morning sun and then some protection from the intense afternoon sun.
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Avoid Full Sun:Direct sunlight can damage the fronds, leading to them drying out and browning.
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Some Sun is Beneficial:While shade is preferred, tree ferns need some sunlight to thrive. They can tolerate dappled sunlight or a few hours of morning sun.
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Species Variation:The exact light requirements can vary depending on the specific species of tree fern.
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Houseplant Care:If growing tree ferns indoors, ensure they receive bright, indirect light and avoid direct sunlight, which can burn the foliage, according to the Brooklyn Botanic Garden.
What is the difference between a tree fern and a fern?
Tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees.
Is tree fern invasive?
Tasmanian tree fern is an invasive plant that’s native to Australia and Tasmania. While it thrives in a broad range of climates, the higher elevation wet forests of the Hawaiian Islands are most at risk. The shade tolerance and long-distance spore dispersal are a dangerous combination for the native forests.
How do you take care of a tree fern?
Plant in peat-free ericaceous compost and place in bright, filtered light. You can grow tree ferns in a large greenhouse or conservatory as long as they are shaded, humid and well ventilated. Avoid indoor temperatures greater than 32°C (90°F).
What is a flying spider monkey tree fern?
Flying spider-monkey tree fern is a stunning tropical plant with a unique appearance. It’s a popular choice for landscaping and indoor decoration due to its beautiful fronds that can grow up to 1.8 m long. The fern is native to Southeast Asia and can tolerate a range of soil types and light conditions.
Can flying spider-monkey tree fern withstand frost?
It can withstand mild frosts. The common name of Flying Spider-monkey Tree Fern is derived from the twisted croziers. The new unfurling fronds-look like monkey arms. General Information: Cyathea lepifera is native to Taiwan, southern China, the Philippines, New Guinea, and the Ryukyu Islands (Japan).
What does the flying spider-monkey tree fern genome tell us?
Huang, X., Wang, W., Gong, T. et al. The flying spider-monkey tree fern genome provides insights into fern evolution and arborescence. Nat.
Are flying spider-monkey tree ferns endangered?
The genome of the flying spider-monkey tree fern and investigations on stem formation and secondary metabolite biosynthesis promote our understanding of fern evolution and arborescence, facilitating the protection and utilization of this endangered species.
Can flying spider monkey tree fern grow in shade?
Flying spider-monkey tree fern is native to environments like forest understories or rocky areas, where it experiences natural shade. Its preferred sunlight condition is partial sun, but it can also tolerate full shade, making it a versatile perennial herbaceous plant. A lack of nutrients will cause a widespread yellowing of the leaves.
How many chromosomes does a flying spider-monkey tree fern have?
Here we assembled the genome of Alsophila spinulosa, known as the flying spider-monkey tree fern, onto 69 pseudochromosomes. The remarkable preservation of synteny, despite resulting from an ancient whole-genome duplication over 100 million years ago, is unprecedented in plants and probably speaks to the uniqueness of tree ferns.