Fern Genome Decoded: Hope for Environmental Sustainability
Unlocking the genetic information of a fern could provide us potential solutions to multiple
issues faced by our planet today.
In genome sequencing, DNA sequencing is done to determine the order of nucleotides in every specific DNA molecule. This exact order is of value for researchers to be able to understand the type of genetic information carried in the DNA. Since genes encode for protein which are responsible for most body functions, this information can help to understand the effect of their function in the body. Sequencing the complete genome of an organism i.e. all of its DNA is a highly complex and challenging task and has to be done bit by bit by breaking DNA into smaller pieces, sequencing them and then putting it all together. For example, the complete human genome was sequenced in 2003 took 13 years and total cost of $3 billion. However, with advancement in technology, genomes can be sequenced relatively faster and also at a lower cost using methods like Sanger sequencing and Next-generation sequencing. Once a genome is sequenced and decoded, unlimited possibilities open up for identifying potential areas of biological research and making progress towards targeted application development.
A team of 40 researchers from Cornell University and around the world have sequenced the full genome of a water fern called Azolla filiculoides1,2. This fern is commonly seen to be growing in warmer temperatures and tropical regions of the world. This project of unravelling the genomic secrets of the fern has been in the pipeline for a while and was backed by a $22,160 from 123 backers through a crowdfunding site called Experiment.com. Researchers eventually received funding to carry out the sequencing from Beijing Genomics Institute in collaboration with Utrecht University. This tiny floating fern species which fits over a finger nail has a genome size of .75 gigabases (or billion base pairs) Ferns are known to have large genomes, average of 12 gigabases in size, however none of the larger fern genomes have been decoded so far. Such an elaborate project was aimed at providing clues on what could be the potential of this fern.
Many interesting aspects of fern Azolla have been uncovered upon this genome sequencing study published in Nature Plants and have provided direction for future research on protential areas in which this fern can be beneficial. The fern Azolla was widespread and growing almost 50 million years ago on this planet around the Arctic Ocean. During that time earth was also warmer compared to current condition and this fern was thought to play a significant role in keeping the planet cooler by capturing around 10 trillion tons of carbon dioxide from the atmosphere over the course of 1 million years. Thus, here we see a potential role for this fern in combating and protecting our planet from global warming resulted by climate change.
The fern is also thought to play an important role in nitrogen fixation, a process which combines free nitrogen (N2) in the atmosphere – an inert gas available abundantly in air - with other chemical elements to create more reactive nitrogen-based compounds e.g. ammonia, nitrates etc which can then be used in various applications like fertilizer for agriculture purposes. The genome data tells us about a symbiotic relationship (mutual benefit) of this fern with a cyanobacteria named Nostoc azollae. The fern leaves host these cyanobacteria in tiny holes and these bacteria fix nitrogen thereby producing oxygen which the fern and surrounding growing plants could use. In turn, cyanobacteria gather energy through the plant photosynthesis when the fern provides it fuel. Therefore, this fern could be possibly used as a natural green fertilizer and possibly eliminate usage of nitrogen fertilizers propagating more sustainable agricultures practises. Authors say that having both the genomes of cyanobacteria and now the fern, research can be clearly focused on developing and adopting such sustainable practises. Interestingly, fern Azolla has already been added in rice paddies as green manure by Asian farmers for more than 1000 years.
Researchers have also identified an important naturally modified (insecticide) gene in the fern which is seen to have the ability to provide insect resistance. This gene when transferred to cotton plants provides massive protection from insects. This ‘insecticidal’ gene is thought to be transferred or ‘gifted’ from bacteria onto the fern and is seen to be a very specific component of the fern’s lineage i.e. it has been passed on successfully from generation to generation. The discovery of potential protection from insects is bound to have a very strong impact on agriculture practises.
This study shows that ‘pure science’ of unravelling first ever genomic information from ferns is a major step in the direction of uncovering and understanding crucial plant genes. This also helps in a better understanding of the evolutionary history of ferns i.e. how their features have evolved over the generations. Authors comment that understanding of plants is very crucial to explore and comprehend how flora and fauna exist together amicably on our planet and such research should be given importance rather than labelling it as something which is not significant enough. After sequencing Azolla filiculoides and Salvinia cucullata, more than 10 fern species are already in pipeline for further research.
1. Fay-Wei Li et al. 2018, ‘Fern genomes elucidate land plant evolution and cyanobacterial symbioses’, Nature Plants, vol. 4, no.7, DOI: https://doi.org/10.1038/s41477-018-0188-8
2. Fernbase, www.fernbase.org, Accessed July 18, 2018.