Variability in expression of insecticidal Cry1Ab gene in Indica Basmati rice

The expression of an insecticidal gene cry1Ab, under three different promoters was studied in leaves, stem and panicles to determine organ-specificity in Basmati rice. Enhanced resistance against two Lepidopteran insects, stem bore (Scripophaga incertulas) and leaf folder (Cnaphalocrocis medinalis) was observed. The result of western hybridization and insect bioassays demonstrated that all these promoters express the cry1Ab gene at similar levels in leaves and panicles. The cry1Ab gene was expressed in stems at 0.05% of the total protein under the control of the PEPC promoter alone or in combination with the pollen-specific promoter. On the other hand it was expressed at 0.15% under the control of the ubiquitin promoter. Southern blot hybridization of these plants indicated integration of the complete plant transcriptional unit at multiple insertion sites. These results demonstrated that a specific promoter could be used to limit the expression of cry1Ab gene in the desired parts of Basmati rice plants.