Pod borer resistant transgenic pigeon pea (Cajanus cajan L.) expressing cry1Ac transgene generated through simplified Agrobacterium transformation of pricked embryo axes

Abstract

Pod borer resistant transgenic pigeon pea (Cajanus cajan L.) plants expressing cry1Ac transgene were generated through Agrobacterium transformation of differentiated and meristematic cells in pricked embryo axes. The uptake of transgene by such cells was expected to produce chimeric T0 plants that were grown to maturity without characterization. The putative transformants were identified from thousands of T1 and T2 seedlings following high throughput paromomycin screening. The presence of transgene in putative T1 and T2 plants was established by polymerase chain reaction and its expression was confirmed in six T2 plants by reverse transcription-PCR and quantitative real time-PCR. The T2 plant PAU 881-21 showed upto 10-fold higher cry1Ac transgene expression as compared to non-transgenic plant. The in vitro bioassay of pods and leaves from PAU 881-21 using third instar Helicoverpa armigera larvae demonstrated 97.78 % larval mortality just after 48 h, pointing towards direct correlation between transgene expression and larval mortality. The pod borer resistant T2 plant PAU 881-21 was phenotypically normal, self fertile and the transgene segregated in 3:1 Mendelian pattern in its T3 progeny.