Scientists Sequence Genome of Flying Spider-Monkey Tree Fern | Sci-News.com

Flying spider-monkey tree fern, scientifically known as Alsophila spinulosais a species of tree fern widely distributed in Asia.

Alsophila spinulosa. Image credit: Quanzi Li.

Land plants evolved 470 million years ago from aquatic algae and have since changed terrestrial ecosystems.

The body of land plants has undergone a series of developmental, biochemical and physiological adaptations, one of which is the emergence of vascular tissue.

In seed plants, xylem, with thickened cell walls, provides stems with high water-conducting efficiency and strong structural support.

Lignin is an important component of the secondary cell wall of xylem – it not only provides mechanical support in fiber cells but also forms a hydrophobic surface in vessels to aid water transport.

Outside of seed plants, tree ferns—members of the order Cyatheales—are one of the few lineages that have tree-like trunks.

This plant has high ornamental value and is considered a resource for natural products with pharmaceutical applications.

Several molecules have been identified to have antitumor and antibacterial activity in tree ferns Alsophila spinulosabut they may represent only a small part of the total diversity of natural products.

Many species of tree ferns are also overexploited, which, combined with climate change, poses a serious threat to their survival.

A better understanding of their recent demographic history will help guide future conservation efforts.

“Ferries were the earliest vascular plants, and lignified cell walls were a key innovation during the evolution of these plants,” said Professor Ray Ming, a researcher in the Department of Plant Biology at the University of Illinois at Urbana-Champaign.

“This study has improved our understanding of how vascular tissue develops in ferns and other land plant species.”

In the study, Professor Ming and colleagues sequenced the genome of Alsophila spinulosa and investigate how its vascular network is constructed.

They found that two Vascular Mac-Domain-associated genes were highly expressed in xylem compared to other tissues, suggesting that these may be key regulators in xylem-specific cell formation.

Using a microscope and biochemical methods, they also measured levels of lignin and secondary metabolites in ferns.

They found that lignin makes up 40% of the stem cell wall. In comparison, wood generally contains 25%.

They also discovered a new secondary metabolite mainly made in xylem, which they named also phyllin.

“This novel compound is abundant in the xylem, possibly as one of the compounds that fills the cavities of dysfunctional tracheid cells,” said Professor Ming.

“We also identified genes involved in alsophilin biosynthesis in the genome.”

To understand how ferns evolved, the researchers compared genome sequences Alsophila spinulosa to other members of the same species at nine sites in China.

To their surprise, they found that there were six distinct populations, differing in their genome sequences.

Based on the results of their sequencing, the authors reconstructed the history of the fern population and saw that there were two times this species experienced a drastic decline in population numbers.

The first occurred 35.6-34.5 million years ago and the second occurred 2.5-0.7 million years ago.

“Analysis of the genome and lignin composition of this broader fern assemblage will help us understand the role of lignin in the early lineage of vascular plants,” said Professor Ming.

“In our future studies, we hope to increase the number of sites and sample sizes for genomic analysis.”

The results are published in the journal Natural Plants.

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X Huang et al. The flying spider-monkey tree fern genome provides insight into fern evolution and arborescence. Nat. Plant 8, 500-512; doi:10.1038/s41477-022-01146-6

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