Using RNAi to block targeted steps in the flavonoid pathway

2 Using RNAi to block targeted steps in the flavonoid pathway 

Targeting F3H appeared less effective. When an RNAi construct for F5H was introduced into tomato, the biosynthesis of flavonoids was reduced beyond this step but not to the extent observed with CHS and FLS. In F3H RNAi fruit peel, rutin levels were decreased to approximately 20% of wild type values (Bovy et al, 2007). This relatively low decrease may have resulted either from just partial downregulation of F3H or because of an intrinsic F3H-like activity of FLS, thereby using naringenin to form flavonols (Lukacin et al, 2003 Martens et al, 2003). Similarly, the simultaneous overexpression of CHS and FLS was sufficient to accumulate flavonols in the fiaiit flesh, despite the very low expression of endogenous CHI and F3H genes in this tissue (Colliver et al, 2002). 

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