Biochemical controls: seed control of 'up' and 'down' (Introduction)

by David Turell , Thursday, May 16, 2024, 18:29 (114 days ago) @ David Turell

The seed knows as described here:

https://www.the-scientist.com/ts-digest/issue/the-shape-of-cilia-24-5?utm_campaign=TS_N...

"More than two hundred years later, attentive observers of vegetation are still working out the molecular mechanisms involved in this process. One of the first major discoveries—the identification of statocytes—occurred in the early 1900s. These cells located in root tips contain heavy, starch-filled granules called amyloplasts that settle to the bottom of the cell. However, said Sophie Farkas, a molecular physiologist at the University of Freiburg, the molecular mechanisms that amyloplasts use to signal which way is down have only recently been elucidated.

"In 2023, researchers found that tipping a plant 90 degrees triggered phosphorylation of proteins called LAZY.3 This caused the LAZY proteins to hop from the cell membrane onto the amyloplasts. Then as the amyloplasts slowly sedimented to the new bottom of the cell, they brought the LAZY hitchhikers with them. When the amyloplast reached its destination, the LAZY proteins hopped off and attached themselves to the membrane on the lower side of the cell.

“'From there, we know that the LAZY proteins recruit other proteins,” said Farkas. Eventually, this leads to recruitment of PIN-FORMED 3 (PIN3), a transporter for the growth-regulating hormone auxin. Subsequently, auxins move to the lower side of the root, where they inhibit growth. If the root is positioned horizontally and grows faster on the upper side than on the lower side, the root is forced to curve downwards, toward the center of the earth."

Comment: the seed knows all before being planted. How did a natural evolution invent that for the seed? Not trial and error. Only design fits.