In planta genetic transformation in pigeonpea: Occurrence and analysis of chimerism in transformants

The recalcitrant pigeonpea was genetically transformed through Agrobacterium-mediated in planta gene transfer method. The agroinfection of pricked cotyledonary embryo axes from 2-day-old germinating seeds resulted in development of 16 cry1Ab PCR positive T₀ plants. The transcription of transgene was detected in 11 plants by semi-quantitative RT-PCR. In planta gene transfer method is documented to produce chimeric plants due to transformation of differentiated and meristematic cells resulting in mixture of transformed and non-transformed shoots. The detection of Cry1Ab protein through ELISA in leaf tissues of some branches from a single T₀ plant indicated presence of chimerism. Further, accumulation of Cry1Ab at variable levels in different leaf tissues revealed quantitative variation for recombinant protein within a single T₀ plant. The distinction of this study pertains to its ability to detect quantitative variation within sectorial chimeras which is not possible through PCR and RT-PCR approaches.