Cloning and characterization of two osmotin isoforms from Piper colubrinum

In the present study, we report the cloning and sequence characterization of two isoforms of osmotin, an antifungal PR-5 gene homologue, from a salicylic acid-induced subtracted cDNA library earlier generated in Piper colubrinum. The larger form of the gene is 693 bp long, encoding a 21.5 kDa protein. The smaller form comprises a 543 bp long coding sequence which code for a protein of 16.4 kDa. A notable feature of the smaller form was a prominent internal deletion of 150 bp besides certain point mutations. Cloned isoforms of osmotin from resistant species could be candidates for molecular breeding for the improvement of black pepper as well as candidates for the study of structure based mechanism of antifungal activity attributed to PR-5 family.