Protease gene families in Populus and Arabidopsis

Maribel García-Lorenzo¹ , Andreas Sjödin² , Stefan Jansson² and Christiane Funk¹

¹Umeå Plant Science Centre, Department of Biochemistry, Umeå University, S – 90187 Umeå, Sweden

²Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S – 90187 Umeå, Sweden

author email corresponding author email

BMC Plant Biology 2006, 6:30doi:10.1186/1471-2229-6-30


Published:	20 December 2006

Abstract

Background

Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution.

Results

We have performed a comparative analysis of protease genes in the two sequenced dicot genomes, Arabidopsis thaliana and Populus trichocarpa by using genes coding for proteases in the MEROPS database [1] for Arabidopsis to identify homologous sequences in Populus. A multigene-based phylogenetic analysis was performed. Most protease families were found to be larger in Populus than in Arabidopsis, reflecting recent genome duplication. Detailed studies on e.g. the DegP, Clp, FtsH, Lon, rhomboid and papain-Like protease families showed the pattern of gene family expansion and gene loss was complex. We finally show that different Populus tissues express unique suites of protease genes and that the mRNA levels of different classes of proteases change along a developmental gradient.

Conclusion

Recent gene family expansion and contractions have made the Arabidopsis and Populus complements of proteases different and this, together with expression patterns, gives indications about the roles of the individual gene products or groups of proteases.