Influence of media supplements on inhibition of oxidative browning and bacterial endophytes of Camellia sinensis var. sinensis.

Explant oxidative browning and necrosis of Camellia sinensis var. sinensis is a severe problem in tissue culture, often associated with the exuded phenolic compounds and microbial contamination from the explants. In this study, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the polyphenol production-required enzyme phenylalanine ammonia lyase (PAL), and different antibiotics were tested to control tea explant necrosis and browning. These compounds were supplemented in the regular plant growth medium together with 6-benzylaminopurine and thidiazuron at different concentrations. Our data indicated that application of 2 µM of AIP was able to effectively inhibit callus browning, significantly reduce EGC abundance, and greatly improve callus induction and growth. Moreover, the use of 150 mg/L of timentin and 30 mg/L gentamycin resulted in an effective elimination of the surface and endophytic microbes associated with explants of C. sinensis var. sinensis. Our study revealed that the inhibition of PAL using AIP combined with the two tested antibiotics could open up new doors to control oxidative tissue browning and endophyte contamination in tissue culture for tea genetic manipulation.