To identify novel genes engaged in plant epidermal development, we characterized the phenotypic variability of rosette leaf epidermis of 310 sequenced Arabidopsis thaliana accessions, focusing on trichome shape and distribution, compositional characteristics of the trichome cell wall, and histologically detectable metal ion distribution. Some of these traits correlated with cLimate parameters of our accession's locations of origin, suggesting environmental selection. A novel metal deposition pattern in stomatal guard cells was observed in some accessions. Subsequent GWAS analysis identified 1546 loci with protein sequence-altering SNPs associated with one or more traits, including 5 genes with previously reported relevant mutant phenotypes and 80 additional genes with known or predicted roles in relevant developmental and cellular processes. Some candidates, including GFS9/TT9, exhibited environmentally correlated allele distribution. Several large gene famiLies, namely DUF674, DUF784, DUF1262, DUF1985, DUF3741, cytochrome P450, receptor-Like kinases, Cys/His-rich C1 domain proteins and formins were overrepresented among the candidates for various traits, suggesting epidermal development-related functions. A possible participation of formins in guard cell metal deposition was supported by observations in available loss of function mutants. Screening of candidate gene lists against the STRING interactome database uncovered several predominantly nuclear protein interaction networks with possible novel roles in epidermal development.

• Keywords
• Arabidopsis thaliana, BioClim, GWAS, guard cell, metal accumulation, phenotypic variability, trichome,
• MeSH
• Arabidopsis * genetics   metabolism   growth & development   MeSH
• Genome-Wide Association Study * MeSH
• Plant Epidermis * metabolism   genetics   growth & development   MeSH
• Phenotype MeSH
• Polymorphism, Single Nucleotide genetics   MeSH
• Metals * metabolism   MeSH
• Plant Leaves * genetics   metabolism   growth & development   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Genes, Plant * MeSH
• Trichomes * growth & development   genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Metals * MeSH
• Arabidopsis Proteins MeSH

Formins are a large, evolutionarily old family of cytoskeletal regulators whose roles include actin capping and nucleation, as well as modulation of microtubule dynamics. The plant class I formin clade is characterized by a unique domain organization, as most of its members are transmembrane proteins with possible cell wall-binding motifs exposed to the extracytoplasmic space-a structure that appears to be a synapomorphy of the plant kingdom. While such transmembrane formins are traditionally considered mainly as plasmalemma-localized proteins contributing to the organization of the cell cortex, we review, from a cell biology perspective, the growing evidence that they can also, at least temporarily, reside (and in some cases also function) in endomembranes including secretory and endocytotic pathway compartments, the endoplasmic reticulum, the nuclear envelope, and the tonoplast. Based on this evidence, we propose that class I formins may thus serve as 'active cargoes' of membrane trafficking-membrane-embedded proteins that modulate the fate of endo- or exocytotic compartments while being transported by them.

• Keywords
• Actin, biotic interactions, cell growth, cytokinesis, endocytosis, exocytosis, formin, microtubules, plasmalemma, tonoplast,
• MeSH
• Cell Membrane * metabolism   MeSH
• Formins * metabolism   MeSH
• Membrane Proteins metabolism   genetics   MeSH
• Plant Proteins metabolism   genetics   MeSH
• Protein Transport * MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Formins * MeSH
• Membrane Proteins MeSH
• Plant Proteins MeSH