Development of transgenic teak (Tectona grandis) expressing a cry1AB genefor control of the skeletoniser

Teak (Tectona grandis) is one of the exotic forest species that has been planted in Malaysia. Teak skeletoniser, Paliga damastesalis, causes minor to considerable damage to teak trees in plantations. We have utilised and modifed a cloned cry1Ab gene to construct a chimeric gene capable of expression in plant cells. Using the Biolistic® particle delivery system, we then transferred the cry1Ab gene into teak cells and regenerated transgenic plants. Te presence and integration of the introduced genes was confrmed by growth of tissue on selection media (MS-10Hm), and by molecular analyses, i.e. Polymerase Chain Reaction (PCR) and PCR-Southern Blotting. PCR analyses for the cry1A(b) gene was carried out on 90 putative transformed teak plants. Te expected internal fragment of 746bp for cry1Ab gene was successfully amplifed from some of the transformants. Te PCR-Southern analyses confrmed the presence of this gene, and RT-PCR analyses confrmed the expression of this transgene in the positive transformants. A bioassay result showed that about 57 cm2 - 66 cm2 of the non-transgenic leaves area showed skeletonisa-tion, whereas only 3 cm2 - 6 cm2 of the transgenic leaves were skeletonised. Te size of the larvae feeding on the control teak leaves increased about 13 to 18 mm. In contrast, larvae feeding on transgenic teak leaves were signifcantly smaller, only 5 to 8 mm. Currently the transgenic teak trees have been successfully planted in a greenhouse at the Forest Research Institute of Malaysia (FRIM)'s nursery.