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Summary The plant hormone auxin and its directional intercellular transport play a major role in diverse aspects of plant growth and development. The establishment of auxin gradients requires the asymmetric distribution of members of the auxin efflux carrier PIN‐FORMED (PIN) protein family to the plasma membrane. An endocytic pathway regulates the recycling of PIN proteins between the plasma membrane and endosomes, providing a mechanism for dynamic localisation. N‐Ethylmaleimide‐sensitive factor adaptor protein receptors (SNAP receptors, SNAREs) mediate fusion between vesicles and target membranes and are classed as Q‐ or R‐SNAREs based on their sequence. We analysed gain‐ and loss‐of‐function mutants, dominant‐negative transgenics and localisation of the Arabidopsis R‐SNARE VAMP714 protein to understand its function.We demonstrate that VAMP714 is essential for the insertion of PINs into the plasma membrane, for polar auxin transport, root gravitropism and morphogenesis. VAMP714 gene expression is upregulated by auxin, and the VAMP714 protein co‐localises with endoplasmic reticulum and Golgi vesicles and with PIN proteins at the plasma membrane.It is proposed that VAMP714 mediates the delivery of PIN‐carrying vesicles to the plasma membrane, and that this forms part of a positive regulatory loop in which auxin activates a VAMP714‐dependent PIN/auxin transport system to control development.

Background Communication systems within and between plant cells involve the transfer of ions and molecules between compartments, and are essential for development and responses to biotic and abiotic stresses. This is turn requires the regulated movement and fusion of membrane systems with their associated cargo. Recent advances in genomics has provided new resources with which to investigate the evolutionary relationships between membrane proteins across plant species. Results Members of the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are known to play important roles in vesicle trafficking across plant, animal and microbial species. Using recent public expression and transcriptomic data from nine representative green plants, we investigated the evolution of the SNARE classes and linked protein changes to functional specialization (expression patterns). We identified an additional three putative SNARE genes in the model plant Arabidopsis. We found that all SNARE classes have expanded in number to a greater or lesser degree alongside the evolution of multicellularity. Sub-functionalization of SNARE family members to different tissues, associated with an accumulation of protein changes is typical, although at least one example of neo-functionalization between the R-SNAREs VAMP722 and VAMP723 was also observed. Conclusion These results provide an insight into SNARE protein evolution and functional specialization. The work provides a platform for hypothesis-building and future research into the precise functions of these proteins in plant development and responses to the environment.

Supplemental material, 2873cc8b46636_EvoBioRevSupplTable4_xyz466366e8025bf for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

Supplemental material, 529d24f646636_EvoBioRevSupplTable6_xyz466362abe5173 for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

Supplemental material, ef0a8cf646636_EvoBioRevSupplTable3y_xyz466366d196b73 for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

Supplemental material, 3185449246636_EvoBioRevSupplTable1_xyz466364bc83175 for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

Supplemental material, f763b0b446636_EvoBioRevSupplTable2_xyz46636386aed71 for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

Supplemental material, 00f8b8c046636_EvoBioRevSupplTable5y_xyz466362fa485fb for Vesicle Transport in Plants: A Revised Phylogeny of SNARE Proteins by Xiaoyan Gu, Adrian Brennan, Wenbin Wei, Guangqin Guo and Keith Lindsey in Evolutionary Bioinformatics

SummaryThe plant hormone auxin and its directional intercellular transport plays a major role in diverse aspects of plant growth and development. The establishment of auxin gradients in plants requires asymmetric distribution of members of the auxin efflux carrier PIN-FORMED (PIN) protein family to the plasma membrane. An endocytic pathway regulates the recycling of PIN proteins between the plasma membrane and endosomes, providing a mechanism for dynamic localization.N-ethylmaleimide-sensitive factor adaptor protein receptors (SNAP receptors, SNAREs) mediate fusion between vesicles and target membranes and are classed as Q- or R-SNAREs based on their sequence. We analysed gain- and loss-of-function mutants, dominant negative transgenics and protein localization of the Arabidopsis R-SNARE VAMP714 to understand its function.We demonstrate that VAMP714 is essential for the insertion of PINs into the plasmamembrane, for polar auxin transport, and for root gravitropism and morphogenesis.VAMP714gene expression is upregulated by auxin, and the VAMP714 protein co-localizes with ER and Golgi vesicles and with PIN proteins at the plasma membrane.It is proposed that VAMP714 mediates the delivery of PIN-carrying vesicles to the plasma membrane, and that this forms part of a positive regulatory loop in which auxin activates a VAMP714-dependent PIN/auxin transport system to control development.