cross-posted from: https://hexbear.net/post/5720376
Nine million years ago, in the shadow of the rising Andes Mountains, a key ancestor of the beloved modern-day potato was born. And now new research shows this pivotal event—and the mashed, baked and fried bounty it routinely delivers today—only happened with crucial help from another treasured kitchen staple: the tomato.
According to a study published on Thursday in Cell, the prehistoric potato precursor was a hybrid of nearby-growing plants in the lineages of the tomato and Etuberosum, a section of species in the genus Solanum. The latter visually resembles the modern-day cultivated potato plant, which is part of the lineage of the Solanum section Petota. But it lacks the ability to produce the distinctive tubers that store all that useful nutrition in a convenient, fist-sized underground package,
“We have always thought that these three lineages were closely related,” says study co-author Sandra Knapp, a research botanist at the Natural History Museum in London. “But what the relationships between those three lineages were [was] not clear; different genes told us different stories. Our group came together to look into the why!”
Knapp and her international team of researchers began by analyzing more than 100 genomes from modern-day potatoes and tomatoes, as well as the largest collection of Etuberosum genomes ever analyzed. The scientists found that each potato genome carried a balanced mosaic of genes from the tomato and Etuberosum lineages. Team members pieced together all the possible phylogenetic trees that could have related the three lineages—and they found strong evidence that the potato was likely not a sister of either the tomato or Etuberosum. The team could then conclude that the potato was a result of a hybridization between the two.
Solanum is the tsundere genus - half of the species want to feed you, the other half to kill you.
On a more serious note:
I did some websearch to check what the SP6A gene does in tomatoes, apparently the SP stands for self-pruning; it probably tells the plant to stop growing an appendage. I couldn't find much info on the IT1 gene from Solanum etuberosum, but if I had to guess it tells the plant to dump carbs in the rhizomes.
If that's correct, IT1 makes the plant keep pumping carbs into rhizomes for further growth, then SP6A says the growth is over, the carbs accumulate and you get a tuber.