A genome-wide association screen for genes affecting leaf trichome development and epidermal metal accumulation in Arabidopsis

We characterized the phenotypic variability of rosette leaf epidermis of 310 sequenced Arabidopsis thaliana accessions, focusing on trichome shape and distribution patterns, compositional characteristics of the trichome cell wall (callose contents, mechanical attachment strength and autofluorescence), and on histologically detectable metal ion distribution. 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 five genes with previously reported relevant mutant phenotypes and 80 additional genes with known or predicted roles in relevant developmental and cellular processes. Several large gene families were overrepresented among the candidates, suggesting epidermal development-related functions. In particular, DUF1262, DUF3741 and receptor-like kinases associated with trichome shape traits, cytochrome P450 paralogs with cell wall composition, Cys/His-rich C1 domain proteins with trichome shape and metal deposition, and formin, DUF674, DUF784 and DUF1985 gene families with metal deposition. 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.