Utilisation of the MVA pathway to produce elevated levels of the sesquiterpene α-copaene in potato tubers

Potato flavour is a complex trait resulting from the presence of a combination of volatile and non-volatile compounds. The aim of this work was to investigate the effect of specifically altering the volatile content of tubers and assess its impact on flavour. Tuber-specific over-expression of a potato alpha-copaene synthase gene resulted in enhanced levels (up to 15-fold higher than controls) of the sesquiterpene alpha-copaene. A positive correlation (R-2 = 0.8) between transgene expression level and alpha-copaene abundance was observed. No significant changes in the levels of volatiles other than alpha-copaene were detected. Non-volatile flavour compounds (sugars, glycoalkaloids, major umami amino acids and 5'-ribonucleotides) were also determined. Relationships between flavour compounds and sensory evaluation data were investigated. Evaluators could not detect any aroma differences in the transgenic samples compared with controls and no significant differences in taste attributes were found. Thus although successful engineering of potato tubers to accumulate high levels of the flavour volatile alpha-copaene was achieved, sensory analysis suggests that alpha-copaene is not a major component of potato flavour. (C) 2011 Elsevier Ltd. All rights reserved.