Exogenous gene transfer in Assam tea [Camellia assamica (Masters)] by agrobacterium-mediated transformation using somatic embryo

A transformation protocol has been standardized in tea (Camellia assamica (Masters), the most economically important perennial woody plant in India, with Agrobacterium tumefaciens strain, LBA 4404 (pCAMBIA 2301; pCAMBIA 1301). This method could be exploited for expression of exogenous gene in tea plants in 15-18 month period. Development of secondary somatic embryos were observed after agroinfection and tested positive for neomycin phosphotransferase II (nptII) and glucuronidase (gusA) genes, regenerated on regeneration media and subsequently multiplied the regenerants. The transformation frequency of A. tumefaciens (LBA 4404) with the binary vector pCAMBIA 2301 and pCAMBIA 1301 on the basis of antibiotic resistance was found to be 2.5% and 3.3% respectively. Further analysis of antibiotic resistant plantlets was done by GUS histochemical assay and polymerase chain reaction (PCR). The PCR positive putatively transformed plantlets were confirmed by Southern blotting for exogenous gene transfer.