This “dual guidance system” was “not predicted”:
Previous studies have shown that microtubules — hollow tubes with a diameter one thousandth of a human hair — play a key role in organising cellulose synthesis. They do this by guiding cellulose synthase complexes (CSCs) — nanomachines that spin cellulose fibres out while travelling along the cell membrane.
But when microtubules are removed by drugs, CSCs continue to journey in an organised way, suggesting another mechanism is at play…
By slowing down microtubules inside growing leaves, spacing them apart and removing them altogether in some experiments, they reveal a system that can independently guide CSCs. In this system CSCs interact with the cellulose trails left by other complexes, like ants following the chemical trails left by other ants.
Further investigation reveals this autonomous system can be overridden by microtubule guidance, allowing the ‘ant columns’ to be redirected in response to environmental and developmental cues.John Innes Centre, “How plants are built to be strong and responsive” at ScienceDaily
Paper. (open access)
Imagine somehow randomly evolving two separate guidance systems…