WRKY Gene Family Evolution In Arabidopsis Thaliana

WRKY genes belongs to the large family of zinc finger transcription factors thatare characterized by a sequence of60amino acids, which contains the WRKYdomain. Many WRKY proteins are involved in salicylic acid (SA) and diseaseresponses as well as wooding, freezing, oxidative stress, drought, heat, cold, andsalinity. Whether the functional divergences are primarily due to adaptive selectionpressure or relaxed selective constraint remains an open question. To evaluate this,we used available WRKY sequences in the public databases to study the molecularevolution of the WRKY gene family and performed a rigorous statistical analysis toevaluate selection pressure following duplication events. Estimates of synonymousand nonsynonymous substitution rates (dN/dS) and more complex branch and sitemodels suggest that purifying selection appears to be the main influence on theevolution of this family and relaxed selective constraints have shaped the evolution ofthe WRKY proteins.