Genome complexity: long-lived fungus (Introduction)

by David Turell , Monday, July 17, 2023, 17:33 (285 days ago) @ David Turell

From competition in the genome:

https://www.sciencealert.com/long-lived-fungi-have-evolved-a-way-to-cheat-death-for-cen...

"The filaments of mushroom-forming fungi spend much of their long lives with two, separate nuclei, each containing one-half of a full set of chromosomes. Only in the gills of mushrooms moments before forming spores do the two haploid nuclei mesh together in a brief union to reproduce asexually.

"Mutations in either nucleus rob the affected mycelium of its ability to fuse its spindly filament to another, forcing other mycelia to pay the cost in spore formation. Given enough time, mutated mycelia will dominate the fungus, reducing its ability to make spores at all.

"First discovered in fast growing Neurospora crassa mold in 2016, the mutated nuclei were dubbed 'cheaters' for the way mutated mycelia can't begin asexual fusion with their own filaments to form spores, but can piggyback off other fully functioning mycelia they may encounter.

***

" 'Because these [fungal] mutations are selected within the mycelium, but reduce the fitness of the mycelium as a whole, you can think of them as a kind of 'nucleus cancers'," explains evolutionary biologist and lead author Duur Aanen, of Wageningen University.

"Aanen and colleagues compared fast-growing molds and long-lived mushroom mycelia that can live for hundreds of years. They suggest the latter use a special type of cell division called a 'clamp connection' to screen against selfish mutants, enabling them to live long lives without amassing too many genetic faults.

"In this form of cell division, one of the filament's haploid nuclei is interned in a holding bay until the cell can check its quality – and that filament fusion is possible.

"'Both nuclei [are] continuously testing each other for the ability to fuse, a test that nuclei with mutations in fusion genes fail," explains Aanen. "If the cell cannot fuse, it means a dead-end for the cell and thus the end of its nucleus."

***

"Though there are some parallels in this new study, fungi are strange beings, comprising a whole other kingdom of life to us animals. So there may be less chance of scientists finding some cellular machinery in fungi capable of quashing cancer that could be relevant to humans."

Comment: fungi and molds are basic constituents of good soils. Perhaps God designed them to last so long to provide that necessary support for soils.