The pattern of plant organ initiation at the shoot apical meristem (SAM), termed phyllotaxis, displays regularities that have long intrigued botanists and mathematicians alike. In the SAM, the central zone (CZ) contains a population of stem cells that replenish the surrounding peripheral zone (PZ), where organs are generated in regular patterns. These patterns differ between species and may change in response to developmental or environmental cues . Expression analysis of auxin efflux facilitators of the PIN-FORMED (PIN) family combined with modeling of auxin transport has indicated that organ initiation is associated with intracellular polarization of PIN proteins and auxin accumulation [2-10]. However, regulators that modulate PIN activity to determine phyllotactic patterns have hitherto been unknown. Here we reveal that three redundantly acting PLETHORA (PLT)-like AP2 domain transcription factors control shoot organ positioning in the model plant Arabidopsis thaliana. Loss of PLT3, PLT5, and PLT7 function leads to nonrandom, metastable changes in phyllotaxis. Phyllotactic changes in plt3plt5plt7 mutants are largely attributable to misregulation of PIN1 and can be recapitulated by reducing PIN1 dosage, revealing that PLT proteins are key regulators of PIN1 activity in control of phyllotaxis.
Bibliographical noteFunding Information:
K.P. was funded by a long-term European Molecular Biology Organization fellowship and by Netherlands Organisation for Scientific Research (NWO) Spinoza and European Research Council advanced investigator grants. G.F.S.-P. was funded by a CBSG2/NCSB grant. Support from NWO-VENI to P.D., NWO-VIDI to I.B., and a Human Frontier Science Program fellowship to A.P.M. is acknowledged. H.H. was funded by NWO-ALW. Work in M.T.’s laboratory was funded by the Biotechnology and Biological Sciences Research Council (BB/F012934/1), the Gatsby Charitable Foundation, and the Royal Society. Live-imaging data were generated by the Microscopy Core at the Institute for Integrative Genome Biology at the University of California, Riverside and were funded by National Science Foundation grant IOS-0718046 to G.V.R.
ASJC Scopus subject areas
- General Biochemistry, Genetics and Molecular Biology
- General Agricultural and Biological Sciences