“How the ‘Diamond of the Plant World’ Helped Land Plants Evolve: Structural Studies of the Robust Material Called Sporopollenin Reveal How It Made Plants Hardy Enough to Reproduce on Dry Land”, 2022-07-19 (; backlinks):
…Tough but Still Edible? Notwithstanding the controversies over their structure for sporopollenin, Fu-Shuang Li and others in the Jing-Ke Weng lab have moved on to another evolutionary question: Has nature figured out how to take apart this nearly indestructible material it put together?
As he hiked around Walden Pond in search of other pollen-coated inlets, Li compared sporopollenin to lignin, the plant polymer that strengthens wood and bark. After woody plants first evolved about 360 million years ago, the geological record shows an abundance of fossilized lignin in strata for tens of millions of years. Then suddenly about 300 million years ago, the lignin vanishes. Its disappearance marks the moment when a fungus called white rot evolved enzymes capable of degrading lignin and ate much of it before it could fossilize.
Sporopollenin, Li reasoned, must also have a fungus or other microbe capable of breaking it down. Otherwise we’d be drowning in the stuff. Li’s back-of-the-envelope calculations are that 100 million tons of sporopollenin are produced in forests every year. That doesn’t even account for the sporopollenin produced by grasses. If nothing is eating it, where does it all go?
This is why, as a source for his latest sample of pollen, Li opted to forgo Amazon Prime in favor of a day at Walden Pond. Observations by his team suggest that some microorganisms grown in petri dishes can survive when fed nothing but sporopollenin and nitrogen. Samples from Walden, which are naturally full of lake microbial communities, should help Li determine whether populations of fungi and other microbes in the wild can unlock the nutrients in sporopollenin’s seemingly unbreakable molecules.
As we snacked on seaweed and granola bars by the pond’s edge, it was easy to see the whole situation from the fungi’s perspective. Nature hates to waste a meal—even one so tough to chew.
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