Plants emerged from 'star algae' to conquer Earth's landmass

Approximately 550 million years ago, the first terrestrial plants evolved from algae and began to transform the Earth’s landscape, drastically altering the planet’s surface and atmosphere..

A significant breakthrough in understanding these origins has been achieved through the collaborative efforts of an international research team, which includes a computational biologist from the University of Nebraska–Lincoln.

This team has successfully decoded the genomic sequence of Zygnema algae, the closest living relatives to these pioneering land plants

Cracking the genomic code

The recent research published in Nature Genetics brought together approximately 50 scientists from eight different countries. This collaboration led to a significant achievement: the first complete genomic sequencing of four different strains of Zygnema algae.

By accomplishing this, the team has provided crucial insights into the evolutionary adaptations that enabled aquatic plants to transition and thrive on land, marking a pivotal development in our understanding of plant evolution.

“This is an evolutionary story,” explained Yanbin Yin, the lead researcher from Nebraska. “It answers the fundamental question of how the earliest land plants evolved from aquatic freshwater algae.”

Significance of Zygnema algae in plant evolution

Zygnema algae are not just another type of plant; they represent a crucial link between aquatic and terrestrial life. The four strains studied — two from a culture collection in the United States and two from Germany — have revealed significant insights into the genomic adaptations necessary for life on land.

Furthermore, advanced DNA sequencing technologies allowed the team to map out the entire genomes, achieving a level of detail previously unattainable for this group. A standout feature identified through this genomic research is the thick, sticky mucilage layer outside the cell walls of the algae.

“It is fascinating that the genetic building blocks, whose origins predate land plants by millions of years, duplicated and diversified in the ancestors of plants and algae, enabling the evolution of more specialized molecular machinery,” noted Iker Irisarri, co-first author of the paper.

Plant genome insights from Zygnema algae

The findings from this study do not just expand our understanding of plant evolution; they also provide a robust resource for the scientific community at large.

Researchers can now delve into these genomic data to explore further connections between plant genetics and environmental responses.

“The entire plant scientific community now has a valuable, high-quality resource to explore these genome data. Our analyses uncovered intricate connections between environmental responses,” said Jan de Vries, another co-leader of the research team.

Foundation for future discoveries

The research aligns with the National Science Foundation’s “Understanding the Rules of Life” initiative, which aims to tackle societal challenges such as climate resilience and clean water.

The gene network analyses from this study reveal that co-expression of genes related to cell wall synthesis and modifications played a crucial role in the evolutionary success of these organisms.

“Our gene network analyses reveal co-expression of genes, especially those for cell wall synthesis and remodifications that were expanded and gained in the last common ancestor of land plants and Zygnematophyceae,” Yin remarked. “We shed light on the deep evolutionary roots of the mechanism for balancing environmental responses and multicellular cell growth.”

Genomic advances propel plant science forward

This research on Zygnema algae marks a significant advance in our genomic understanding of plant life’s origins on land.

The collaborative effort underscores the importance of international cooperation in scientific research, uniting diverse expertise to unravel complex biological puzzles.

The genomic insights gained extend beyond academia, impacting fields such as bioenergy, water sustainability, and carbon sequestration.

This work not only deepens our comprehension of our planet’s ecological history but also equips us with the knowledge to better tackle some of the most pressing environmental issues of our time.

The full study was published in the journal Nature Genetics.

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