Evaluation of the Genetic Variation in the Abscisic Acid Receptor Binding Site Across Ten Monocot and Dicot Species

Abscisic acid (ABA) is a phytohormone known to mediate both developmental processes and responses to environmental stress factors in plants.  Recent reports have identified a genetically redundant family of ABA receptors, represented by fourteen homologues in Arabidopsis thaliana, entitled Regulatory Component of ABA Receptor (RCAR) / Pyrabactin Resistant 1 (PYR1) / Pyrabactin Resistant-Like (PYL) receptors.   Now we have mined the available genomic databases and literature for five monocot and four additional dicot species for representative RCAR genes.  In all instances, families of homologous RCAR genes were identified, with members falling into some or all of the three previously defined RCAR clades.  Sequence comparison of residues comprising the ABA-binding site and phosphatase interacting interface in receptors from different clades and different species highlight some potentially significant variations.  A select number of these variations were modelled structurally in silico.  The potential impact of clade and species-specific variations are discussed.  This work was supported by NRC and Valent Biosciences Corp.