Genetic diversity of NMT gene in coffee using SCAR marker
Dr. Neeta Shivakumar, Dr. Pushpa Agrawal
Coffee tree belongs to the genus Coffea comprising of two main cultivated species C arabica L. and C. caenophora and third sparsely grown species C liberica in some parts of Africa. Importantly, many of these diverse species hybridize readily with each other and thus are a rich and valuable source of desirable genetic variability for improvement of cultivated coffee germplasm. But breeding coffee has been difficult because of a variety of genetic and environmental factors. Also, the caffeine in coffee is a major source of health problems in the developed and in the developing nations. One solution would be to develop coffee varieties which have less caffeine or caffeine free, retaining their flavour using the gene manipulation techniques or by using molecular markers. It has been found that three genes namely, 7-methyl xanthosine synthase (CAXMT1/CmXRS1), two theobromine synthases (CAMXMT1/CTS1 AND CAMXMT2/CTS2) and caffeine synthase (CADXMT1/CCS1) are responsible for the synthesis of caffeine in the coffee plant. Hence an attempt has been made to construct gene specific markers (SCAR marker) and confirm the presence of genetic diversity for NMT gene in coffee in few of the South Indian varieties. Also the genetic diversity of NMT gene both in coding and non coding region was chequed. The genetic diversity recognized by the SCAR marker is very similar, although the diversity is very narrow for the NMT gene.