Mining and characterization of Allium cepa expressed sequence tags (ESTs) encoding receptor-like kinases (RLKs)

Plant receptor-like kinases (RLKs) are comprised of a large family of kinases having multitudinous functions. Onion (Allium cepa), an important bulbous plant, has almost no reports on RLKs and their role in onion plant growth and defense responses. In the present work, mining of the transcript database ‘dbEST’ has been performed to obtain the expressed tags of A. cepa. Subsequently, the consensus sequence assembling carried out by CAP3 program resulted in 4175 number of contigs. Consecutive rounds of BLAST searches resulted in identification of 4 highly homologous contigs with the previously reported plant RLKs. Further structural characterizations by MEME, Prosite and SOPMA supported the identified contigs to be putative RLKs. All four putative RLKs (AcCon13, AcCon183, AcCon383, and AcCon1738) possessed 9 out of 11 canonical kinase sub-domains, the signature protein-kinase domain, and the ATP binding sites. Phylogenetic analysis along with previously reported plant RLKs revealed that the identified contigs belong to different RLK sub-families.