Molecular Characterization of Calotropis procera and the Calotropain Gene

Calotropis procera (Ait) W.T. Aiton, also known as Sodom apple, is a member of the Apocynaceae family, which produces milk-like latex. C. procera is regarded in many regions as weed that grows as a perennial shrub in subtropical and tropical regions overtaking open land areas and pastures. However, it is also appreciated for its fibers, its various medicinal applications (e.g. antimicrobial, anti-inflammatory), and its use for cheese making. In Benin, the major center for cheese-production in the West Africa region aqueous extracts from C. procera are used to produce the traditional cheese, called Peulh. Calotropain, a cysteine protease, is the major ingredient responsible for the milk clotting activity. However, so far only locally grown native C. procera is used for this purpose. We isolated the whole Calotropain gene from an accession KG1 of Kandi Green in Benin by using gene specific primers as well as 5’- and 3’-RACE.  The gene consists of four exons. The coding sequence is 1026 bp long, encoding a protein of 341 amino acids. The amino acid sequence contains the highly conserved motifs ERFNIN and GNFD, which are characteristic for cysteine peptidase of the C1A subfamily. Using the genetic diversity within the different C. procera accessions we hope to be able to develop a breeding program for C. procera with regard to improving the milk clotting activity for cheese production.