Natures wonders: fungal symbiosis by gene loss (Introduction)

by Balance_Maintained @, U.S.A., Sunday, September 30, 2018, 19:13 (647 days ago) @ David Turell

The fungus had to lose dangerous attack proteins in order to join in the symbiotic relationship:

" Most Amanitas can only survive by closely partnering with plants, providing their roots with minerals and nutrients in exchange for sugars. This symbiosis evolved more than 50 million years ago and helps forest ecosystems thrive.


"To get at what separated symbiotic from free-living Amanitas, the researchers sequenced the genomes of three symbiotic Amanita species -- including the fly amanita -- and three close relatives that aren't symbiotic. The genomic sequences allowed them to reconstruct the evolutionary paths that led to the fungi's different adaptations.

"'We went into this thinking we'd find commonalities between the three symbiotic Amanitas," Pringle says.

"But despite their similar lifestyles, symbiotic Amanitas looked vastly different from one another on the genomic level.(MyBold) Some symbiotic species had almost double the number of genes as their similarly symbiotic relatives. The symbiotic mushrooms seemed to take different genomic paths after they first diverged, developing unique ways to tailor their partnership with plants.

"Earlier research on other families of mushrooms had suggested that one defining characteristic of symbiotic lifestyles was the loss of enzymes capable of degrading the cellulose-laden walls of plant cells. These genes are crucial for decomposers eating through leaf litter. But for fungi that associate with plants and must avoid harming their partners, cellulose-digesting enzymes are only a liability.

"So when Pringle, Hess and their team looked at this group of digestive enzymes, they were surprised to find that the free-living species Amanita inopinata was missing these genes. Although symbiotic Amanita mushrooms had indeed lost this suite of digestive enzymes, Amanita inopinata's lack of them meant the researchers couldn't link this loss to symbiosis itself.

"Pringle says the unexpected absence of cell wall-digesting genes in Amanita inopinata's genome may actually be a clue pointing to evolution at work. If symbiosis only develops once fungi let go of these digestive enzymes, the researchers reason, then Amanita inopinata may be primed to evolve a closer partnership with plants.

"Not quite symbiotic, perhaps not fully independent, Amanita inopinata seems to be "stuck between two worlds," says Hess, who began the work while a postdoctoral researcher in the Pringle lab and is now a senior scientist at the University of Vienna.

"The evolution of Amanita inopinata -- "the unexpected one," in Latin -- and the other Amanitas also seem to support a developing consensus that symbiosis, once thought to be exceptional, may actually be easy to evolve. The researchers didn't find that Amanita needed to develop a new, complex suite of genes in order to start partnering with plants. Instead, just letting go of a few once-vital genes may be sufficient to forge new relationships in nature."

Comment: Note my bold. This symbiosis could only happen if genes were lost, because they had to be absent. Looks like design to me; not by chance.

So, three fungi with 'vastly different' genomic sequences are classified as the same, thus genes had to be lost. What? With this kind of logic, anything can be evolution. Oh look! My cat turned into a toaster strudel!

What is the purpose of living? How about, 'to reduce needless suffering. It seems to me to be a worthy purpose.

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