Plants use precise location and timing to produce leaves and flowers
Researchers at the Hebrew University of Jerusalem have discovered that the hormone auxin regulates leaf development in tomato plants through precise timing. By briefly lowering levels of the growth hormone gibberellin, auxin initiates leaflet formation before later promoting blade expansion.
Why it matters
This finding clarifies a long-standing biological puzzle regarding how a single hormone can trigger two distinct, opposing developmental processes in plant growth.
A tomato plant builds each leaf in a set order. It first marks where a new leaflet will form, then lets that spot grow into a full blade.
One hormone, called auxin, controls both steps. But how a single signal could start a new leaflet and later expand it was never clear.
Auxin rarely acts alone inside a plant. In most situations, it raises the level of a second growth hormone, gibberellin, so the two usually promote growth at the same time.
That textbook relationship made the tomato leaf a real puzzle. If auxin only ever increased gibberellin, one hormone could not both start a new leaflet and later drive its growth.
A team led by Dr. Alon Israeli set out to watch the two hormones during leaf building. The work came from the lab of Professor Naomi Ori at the Hebrew University of Jerusalem .
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