A Division in PIN-Mediated Auxin Patterning during Organ Initiation in Grasses

• DOI: 10.1371/journal.pcbi.1003447
• Publication Date: 2014-01-30T21:54:23Z
• Authors: Devin L. O'Connor; Adam Runions; Aaron Sluis; Jennifer Bragg; John P. Vogel; Przemyslaw Prusin...; Sarah Hake
• Keywords: Primordium; Brachypodium distachyon; Pericycle; Epidermis (zoology); Phyllotaxis; Vascular tissue

The hormone auxin plays a crucial role in plant morphogenesis. In the shoot apical meristem, PIN-FORMED1 (PIN1) efflux carrier concentrates into local maxima epidermis, which position incipient leaf or floral primordia. From these maxima, PIN1 transports internal tissues along emergent paths that pattern and stem vasculature. Arabidopsis thaliana, functions are attributed to single protein. Using phylogenetic gene synteny analysis we identified an angiosperm PIN clade sister PIN1, here termed Sister-of-PIN1 (SoPIN1), is present all sampled angiosperms except for Brassicaceae, including Arabidopsis. Additionally, conserved duplication of grasses: PIN1a PIN1b. Brachypodium distachyon, SoPIN1 highly expressed epidermis consistently polarized toward regions high expression DR5 auxin-signaling reporter, suggests localization new contrast, PIN1b tissues, suggesting vascular patterning. broad spanning space between primordia previously formed vasculature, connecting organs sinks older tissues. Within regions, forms narrow canals likely future veins. computer model, reproduced observed spatio-temporal patterns proteins by assuming up gradient, different degrees with flux. Our results suggest examination modeling dynamics plants outside Brassicaceae will offer insights auxin-driven patterning obscured loss Brassicaceae.