What is it about?

In plants, the hormone auxin is carefully transported throughout the plant body. This is essential for normal plant growth and is carried out by specific auxin transport proteins known as PINs. Auxin transport by PINs, and thereby plant growth, is inhibited by the chemical NPA. We show that NPA binds directly to PINs to inhibit their auxin transport activity.

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Why is it important?

NPA has been used for decades by plant scientists to help understand why auxin transport is so important for plant growth. However, scientists did not know exactly how NPA manages to inhibit auxin transport. PINs are responsible for auxin transport, but evidence of a direct interaction of NPA with PINs was missing, so alternative complicated schemes for NPA action were instead hypothesized. Our study now shows that NPA can indeed bind directly to PINs to inhibit their auxin transport activity. This provides the simplest of all answers and confirms a long-suspected but never-proven direct link between NPA and PINs. This will enhance the use of NPA in future studies and may also help reveal mechanistic and structural aspects of PINs as transporters.

Perspectives

I started this work thinking the answer would be "No", as it seemed plausible to assume that others had looked for a link before and failed to find one. Being your own biggest skeptic, and also having to go against the norm and compete with previously established models, meant that the bar was set much higher than normal, first by us and then later by the reviewers. It made me wonder where a bar should "normally" be placed. Shouldn't we try more often to set the bar higher than normal? In the publish-or-perish world of today and the pressure to get things out as quick as possible, does "how-low-can-you-go" happen more often?

Lindy Abas
Universitat fur Bodenkultur Wien

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This page is a summary of: Naphthylphthalamic acid associates with and inhibits PIN auxin transporters, Proceedings of the National Academy of Sciences, December 2020, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2020857118.
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