PIN‐FORMED is required for shoot phototropism/gravitropism and facilitates meristem formation in Marchantia polymorpha. Issue 4 (28th March 2023)

• Record Type: Journal Article
• Authors: Fisher, Tom J.; Flores‐Sandoval, Eduardo; Alvarez, John P.; Bowman, John L.
• Is Part Of: New phytologist. Volume 238:Issue 4(2023)
• Page Start: 1498
• Page End: 1515
• Publication Date: 2023-03-28
• Subjects: auxin -- land‐plant evolution -- Marchantia polymorpha -- PIN‐FORMED -- polar auxin transport; Botany -- Periodicals; 580
• DOI: 10.1111/nph.18854
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: PIN‐FORMED auxin efflux transporters, a subclass of which is plasma membrane‐localised, mediate a variety of land‐plant developmental processes via their polar localisation and subsequent directional auxin transport. We provide the first characterisation of PIN proteins in liverworts using Marchantia polymorpha as a model system. Marchantia polymorpha possesses a single PIN‐FORMED gene, whose protein product is predicted to be plasma membrane‐localised, Mp PIN1 . To characterise MpPIN1, we created loss‐of‐function alleles and produced complementation lines in both M. polymorpha and Arabidopsis. In M. polymorpha, gene expression and protein localisation were tracked using an Mp PIN1 transgene encoding a translationally fused fluorescent protein. Overexpression of Mp PIN1 can partially complement loss of an orthologous gene, PIN‐FORMED1, in Arabidopsis. In M. polymorpha, Mp PIN1 influences development in numerous ways throughout its life cycle. Most notably, Mp PIN1 is required to establish gemmaling dorsiventral polarity and for orthotropic growth of gametangiophore stalks, where Mp PIN1 is basally polarised. PIN activity is largely conserved within land plants, with PIN‐mediated auxin flow providing a flexible mechanism to organise growth. Specifically, PIN is fundamentally linked to orthotropism and to the establishment of de novo meristems, the latter potentially involving the formation of both auxin biosynthesis maxima and auxin‐signalling minima.