Poster: Comparative Genomics

Abs # 914: A Phylogenomic Study of the ILR1-like IAA Amidohydrolase family of genes

Presenter:	Campanella, James J, Campanellj@mail.montclair.edu
Authors	Campanella, James J (A)   Larko, Daniel  (A)   Smalley, John  (A)
Affiliations:	(A): Montclair State University

The ILR1-like family of hydrolase genes was initially isolated in Arabidopsis and regulates levels of free indole-acetic-acid. We have investigated how this family has evolved in plant species genetically distant from Arabidopsis by employing the GenBank and TIGR databases to retrieve orthologous genes for family members in grape, pine, cotton, clover, soybean, barley, tomato, potato, corn, sorghum, lotus, wheat and rice. The relationships among these sequences were assessed employing phylogenetic analysis to examine molecular evolution and phylogeny. The members of the ILR1-like family with multiple orthologous genes were ILR1, IAR3 and ILL3; searches with ILL1, ILL2 and ILL5 sequences produced too few orthologs for practical analysis. IAR3 has undergone the least evolution based on its low levels of molecular divergence and large number of interspecifc orthologs. The monocotyledonous orthologs for ILR1 have evolved into a separate molecular clade from dicotyledons, indicating active evolutionary change. However, protein sequence analysis of ILR1 suggests high conservation at the protein level, despite changes in the primary coding sequences. Based on this conservation, IAR3 and ILR1 may have had a major role in the physiological evolution of "higher" plants. ILL3 is least conserved with high divergence and fewest orthologs. ILR1 and IAR3 are orthologous to the gymnosperm Pinus taeda, indicating an ancient enzymatic activity. No orthologs could be detected in moss and fern databases.