Because of the central position of UDP-Glc in carbohydrate metabolism6, being situated at
the branching point of various competing sinks for carbon74, UGD activity was selected to be
manipulated in order to increase the flux of carbon moieties into sucrose. To analyse the
effect of decreased UGD on sucrose accumulation in sugarcane, ‘antisense’ technology and
intron-spliced hairpin RNA vectors were constructed and transformed into embryogenic
sugarcane calli. Nine sugarcane lines transformed with the antisense vector (pAUGdf510)
and four lines transformed with the ihpRNA vector (pHan-UGD) were raised. Northern
analysis and RT-PCR indicated that the transformed lines had decreased UGD transcript
levels and Southern analysis showed that all lines were unique transformation events. Four
lines showing antisense repression of UGD transcription were chosen for more detailed
characterisation.