Article discussion: What do Phytochromes do in roots?

A couple of days ago Magdalena Julkowska (https://twitter.com/mmjulkowska) asked in a tweet what my opinion is about a recent article

Would love to hear what @ronaldpierik@GelderenKasper think about this paper!

— Magdalena Julkowska (@mmjulkowska) May 17, 2018

So Magda, this one is especially for you 🙂

She asked this, because she knows that this topic is of great interest to me. So what is it?
The article “Root‐expressed phytochromes B1 and B2, but not PhyA and Cry2, regulate shoot growth in nature”, by Oh et al., from the Ian Baldwin lab, was recently published in Plant Cell and Environment. It tries to address the question what the role is of the phytochrome light receptors in plant roots, which obviously grow in an environment of relative darkness.

This is a topic which we ourselves have discussed as well, although as a sideline from the main part, in two recent articles:…