Cut lettuce in the fridge yellows within a few days. The plant isn't simply dying: it switches on a program that destroys the green pigment chlorophyll. This program has its own conductor, the LsMAX1 gene. It makes the plant produce hormones called strigolactones, which set the yellowing in motion.
When the LsMAX1 gene was switched off, lettuce leaves kept far more chlorophyll after eight days of darkness. The usual aging genes barely turned on. But instead, stress genes activated, the ones that help a plant survive harsh conditions. Aging didn't stop; the plant just chose a different way to cope.
Researchers used to think strigolactones simply speed up aging. Now it's clear they determine which genes get switched on. Disable that signal, and the plant takes a backup route. This finding could help breed lettuce varieties that stay fresh longer.
Strigolactones take their name from the parasitic plant Striga, whose seeds germinate once they sense these compounds in a host's root exudates.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.