Scientists have been baffled for decades by the signal plants send to initiate photosynthesis and the process of converting sunlight into sugars. But these cryptic signals have now been decoded by UC Riverside researchers.
Botanists have known for over a half-century that the nucleus (the command centre of a plant cell) sends instructions to other parts of the cell. It compels them to continue photosynthesis. Plants cannot turn green or grow without these instructions and it take the form of proteins.
The method used by Chen’s lab scientists to discover four of these proteins is now documented in a Nature Communications paper.
Previously, Chen’s team have demonstrated that light activates specific proteins in plant nuclei. It triggered photosynthesis. These four newly discovered proteins are involved in that reaction. These proteins sent a signal that converts small organs into chloroplasts and it produced growth-promoting sugars.
Chen likens the photosynthesis process to a symphony.
The symphony is performed in two “rooms” within the cell, by both local (nucleus) and remote musicians. The conductors (photoreceptors), which are only found in the nucleus, must send messages to the musicians who are located elsewhere. The four newly discovered proteins that travel from the nucleus to the chloroplasts control this final step.
The National Institutes of Health funded this research in the hopes of finding a cure for cancer. The similarities between chloroplasts in plant cells and mitochondria in human cells give rise to this optimism. Both organelles produce fuel for growth and contain genetic material.
A lot of current research focuses on communication from organelles back to the nucleus. If the organelles detect a problem, they will send a signal to the nucleus “headquarters.” Much less is known about the nucleus-to-organelle activity-regulating signals.
Understanding how photosynthesis is controlled has implications beyond disease research. Human settlements on another planet would almost certainly necessitate indoor farming. Climate change is posing immediate challenges for crop growers around the world.
More information: Youra Hwang et al, Anterograde signaling controls plastid transcription via sigma factors separately from nuclear photosynthesis genes, Nature Communications (2022). DOI: 10.1038/s41467-022-35080-0