title: Natural variation in stomatal abundance of Arabidopsis thaliana includes cryptic diversity for different developmental processes.
abstract: OBJECTIVE
  Current understanding of stomatal development in Arabidopsis thaliana is based on mutations producing aberrant, often lethal phenotypes. The aim was to discover if naturally occurring viable phenotypes would be useful for studying stomatal development in a species that enables further molecular analysis.
  
  
  METHODS
  Natural variation in stomatal abundance of A. thaliana was explored in two collections comprising 62 wild accessions by surveying adaxial epidermal cell-type proportion (stomatal index) and density (stomatal and pavement cell density) traits in cotyledons and first leaves. Organ size variation was studied in a subset of accessions. For all traits, maternal effects derived from different laboratory environments were evaluated. In four selected accessions, distinct stomatal initiation processes were quantitatively analysed.
  
  
  CONCLUSIONS
  Substantial genetic variation was found for all six stomatal abundance-related traits, which were weakly or not affected by laboratory maternal environments. Correlation analyses revealed overall relationships among all traits. Within each organ, stomatal density highly correlated with the other traits, suggesting common genetic bases. Each trait correlated between organs, supporting supra-organ control of stomatal abundance. Clustering analyses identified accessions with uncommon phenotypic patterns, suggesting differences among genetic programmes controlling the various traits. Variation was also found in organ size, which negatively correlated with cell densities in both organs and with stomatal index in the cotyledon. Relative proportions of primary and satellite lineages varied among the accessions analysed, indicating that distinct developmental components contribute to natural diversity in stomatal abundance. Accessions with similar stomatal indices showed different lineage class ratios, revealing hidden developmental phenotypes and showing that genetic determinants of primary and satellite lineage initiation combine in several ways. This first systematic, comprehensive natural variation survey for stomatal abundance in A. thaliana reveals cryptic developmental genetic variation, and provides relevant relationships amongst stomatal traits and extreme or uncommon accessions as resources for the genetic dissection of stomatal development.
authors: Departamento de Ciencias Ambientales, Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avda. Carlos III s/n, Toledo, Spain.
authors: Dolores
authors: D
authors: Delgado
authors: Carlos
authors: C
authors: Alonso-Blanco
authors: Carmen
authors: C
authors: Fenoll
authors: Montaña
authors: M
authors: Mena
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D018548:Cotyledon / Q000166:cytology / Q000254:growth & development; D004777:Environment; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D010641:Phenotype; D019441:Plant Epidermis / Q000166:cytology; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics; D054046:Plant Stomata / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D018526:Plant Transpiration / Q000502:physiology; D040641:Quantitative Trait Loci