Genome wide analyses of the caffeic acid o-methyltransferase gene family in Populus

Open Access
Author:
Choi, Alex
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Sarah Mary Assmann, Thesis Supervisor
  • Abdelali Barakat, Thesis Supervisor
  • John Edward Carlson, Thesis Supervisor
  • Sarah Mary Assmann, Honors Advisor
Keywords:
  • COMT
  • lignin biosynthesis
  • phylogeny
  • expression
  • gene organization
Abstract:
Background Monolignols are basic components of lignin; their synthesis involves a dozen enzymes. Caffeic acid o-methyltransferase (COMT) is one of the key enzymes involved in the synthesis of monolignols. The COMT gene family has been studied in several species, including model and non-model plants. Here we analyzed the organization, the phylogeny, and the expression of COMT genes in various tissues from non-stressed and stressed Populus plants. Results We identified 8 COMT genes from Populus and found that all of them are located in duplicated blocks. COMT genes are distributed in two phylogenetic classes with the real COMT gene distributed in Class I. Expression profiling showed that COMT genes present various expression profiles in leaves, bark, and xylem from poplar. One gene, which was previously described as a real COMT gene, showed preferential expression in xylem tissue. The others are either preferentially expressed in bark or show no differential expression. Conclusions COMT genes are highly duplicated and most of duplicates are still in conserved positions on homeologous blocks wthin the Populus genome. Expression profiling showed that COMT genes present different expression profiles in Populus tissues with only one gene differentially expressed in xylem. Our results suggest that COMT genes have evolved various expression profiles and may have evolved different functions following duplications.