CBN-V Video Archives - S7-30
A PAL Promoter Isolated from Deteriorating Cassava Roots Drives Highly Specific Marker Gene Expression in Transgenic Plants

Taylor N.J.¹, Hongying Li², J.R. Beeching² and C.M. Fauquet¹

1. International Laboratory for Tropical Agricultural Biotechnology (ILTAB), Danforth Plant Science Center, 975 Warson Road, St Louis, MO 63132 iltab@danforthcenter.org
2. Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK J.R.Beeching@bath.ac.uk

        Improving the post harvest durability of cassava roots would have a significant impact on the crop’s utilisation and commercialisation throughout the tropics. In order to understand gene expression in deteriorating roots, the promoter from a PAL gene, previously isolated from cassava storage roots at the University of Bath, was fused to the uidA visual marker gene. Transgenic cassava, tobacco and rice were genetically transformed with the PAL-uidA cassette and the recovered plants analysed for marker gene expression by GUS and MUG assays. Both the monocot and dicot species expressed GUS. The PAL promoter drove strong expression in embryogenic callus of both cassava and rice but was rapidly down regulated in regenerated plantlets. In rice plants, histological examination showed GUS expression to be limited to the bundle sheaths, guard cells, anthers and pollen. In cassava strong, highly specific expression was observed in the xylem parenchyma and cork cambium in both the shoot and root systems. A similar pattern was evident in tobacco with only the xylem parenchyma and pollen showing visible expression. Evidence for the action of this promoter in root deterioration was seen by a significant increase in MUG activity 24 hrs after removal of the root from the mother plant and specific localisation of GUS expression to those cells which are first to undergo phenolic deposition during the deterioration process.

For further information, see spoken presentation Taylor et al. S7-31

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