The group of WANG Yong at SIBS Institute of Plant Physiology and Ecology succeeded to design a biosynthetic pathway based on 4 modules which were separately optimized and led to good yields of the desired steviosides. The membrane-associated cytochrome P450 enzyme KAH was identified as the rate-limiting step. To relieve this bottleneck, an engineered CYP714A2 from Arabidopsis thaliana replacing KAHn2 significantly improved the yield of steviol to 15.47 mg l-1. Furthermore, by subsequently incorporating the UGT module, 10.03 mg l-1 of rebaudioside A, the major component of native stevia extracts, was successfully produced in shake flask among various kinds of SGs.

CAS news release, September 17, 2015