For the first time, a research team led by the Chinese Academy of Forestry in Beijing and the University of Illinois at Urbana-Champaign has thoroughly investigated the genomic arrangement of tree ferns, offering new understandings of how these plants evolved.
As specified in the Earth.com report, "land plants evolved 470 years ago from algae," and, from that time, they essentially reshaped the Earth.
During their evolution, ferns underwent various changes that helped them survive and flourish on land.
The scientists said a major breakthrough in the land plants' evolution involved their vascular systems' invention, which helped them conduct water and nutrients through their bodies.
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Researchers investigated the genomic arrangement of tree ferns, revealing how the species grew, reproduced, and dropped over millions of years.
Xylem and Phloem
Such systems comprise two tissues, including the xylem and the phloem. While the xylem facilitates the water's transport to the leaves and stems, the phloem helps transport sugars generated through photosynthesis to the remaining parts of the plant.
Furthermore, xylem cells are lined with a supporting structural material called lignin that offers rigidity to wood and bark.
According to Plant Biology Professor and the study's senior author, Ray Ming from the University of Illinois, ferns are the "earliest vascular plants, and lignified cell walls" was a key innovation during these plants' evolution.
This research published in the Nature Plants journal has improved insight into how vascular tissues developed in ferns and other land plant species.
Spider-Monkey Tree Fern Sequenced
Through sequencing of the genome of the flying spider-monkey tree fern Alsophila spinulosa, which is described on the iNaturalistAU website, Ming, together with colleagues, found that two vascular-related Mac-Domain genes were highly expressed in this xylem of fern compared to other tissues suggesting that they might be key controllers in the xylem-specific cells' formation.
The researchers measured as well the levels of lignin, as well as secondary metabolites, compounds that are not needed for growth and reproduction, although nonetheless provide some benefits, in ferns, and discovered that lignin comprises 40 percent of the stem cell wall.
Furthermore, the team also identified a new secondary metabolite mainly made in xylem, which they identified as "alsophilin."
Such a new compound is abundant in the xylem, such as one of the compounds that file up the cavity of non-functional tracheid cells.
Professor Ming also said they could identify the genes involved in the biosynthesis of alsophilin in the genome.
Drastic Drop Twice in Fern Species
To understand the ferns' manner of evolution, the scientists compared the genome of A. spinulosa to other members of the same species spread throughout China.
Astonishingly, the researchers identified six distinct populations with different genomic sequences. Based on the findings, the experts rebuilt the evolutionary background of ferns and found that such species went through a drastic drop two times, approximately 35 million and 2.5 million years ago.
This particular analysis of genomes and the lignin composition from a broader collection of ferns helps scientists understand the function of lignin in the early lineage of vascular plants.
Finally, Ming said, in their future research, they hope to increase the number of sites and the sample sizes for the genomic assessment.
Related information about fern plants is shown on Novita Listyani's YouTube video below:
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