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S10-04
The role of scopoletin in cassava postharvest physiological
deterioration (PPD)
Shi Liu1*, Ima M. Zainuddin2, Herve Vanderschuren2, James Doughty1 and John R.
Beeching1
1) Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom, BA2 7AY,
2) Department of Biology, ETH Zurich, Zurich, Switzerland.
* [email protected], Registrant ID# 1066
The wounds caused during the harvest of cassava (Manihot esculenta Crantz) activate a
series of spontaneous physiological responses collectively known as postharvest
physiological deterioration (PPD), which causes the roots to become unpalatable and
unmarketably within 24 - 72 hours of harvest. During this response the hydroxycoumarin
scopoletin accumulates to high levels in cassava roots and its oxidation plays an important
role in PPD. In the Arabidopsis thaliana scopoletin biosynthetic pathway the expression of
the gene F6’H1 (At3g13610) is essential for the synthesis of scopoletin. We have identified
a small family of seven genes in the cassava genome that show high homology to F6’H1.
Three of these family members, when expressed in T-DNA insertion mutants of F6’H1 in
Arabidopsis complement the mutation and restore the synthesis of scopoletin. Transgenic
cassava (cultivar TMS 60444) containing RNAi constructs, driven by either the constitutive
CaMV 35S or root-specific potato patatin promoters, with the potential to inhibit the
expression of the cassava homologues have been made. Here we present data on the
expression of these constructs in the transgenic lines, their effect on scopoletin
accumulation and on the PPD response.