title: Comparative performance of modified full-length and truncated Bacillus thuringiensis-cry1Ac genes in transgenic tomato.
abstract: BACKGROUND
  Bt-cry1Ac gene has been reputedly effective against Helicoverpa armigera a notorious lepidopteran pest. Reports on the expression of full-length and truncated cry1Ac genes in plants for effective resistance against Helicoverpa sp. have been documented however, their performance is still ambiguous. Moreover, the question remains to be addressed that truncation of 3' end of the native gene was documented and suggested for active insecticidal toxin production while the most successful transgenic event(s) of commercialized-cotton are based on full-length of the cry gene. Therefore, we performed a comparative study on the efficacy of the two versions of cry1Ac genes (full-length: 3,510 bp and truncated: 1,845 bp) in T0 and T1 transgenic tomato plants and analyzed the extent of protection against H. armigera and also compared the results with our previous findings related to a successful transgenic tomato line Ab25E, expressing cry1Ab gene. The integration of cry1Ac gene(s) in T0 transgenic plants and its inheritance in T1 progeny was observed by PCR, RT-PCR and Southern blot hybridization analysis while, the toxin integrity, expression and toxicity was monitored by Western immunoassay, DAS-ELISA and insect bioassay respectively.
  
  
  RESULTS
  An average transformation frequency and Bt-Cry protein content of 16.93 ± 2.10 and 0.0020-0.0128% of total soluble protein (TSP) was obtained with pRD400 vector (Trcry1Ac) while, a much lower value of 9.30 ± 2.041 and 0.0001 - 0.0026% of TSP was observed with pNBRI-1 vector (Flcry1Ac), respectively. The promising Trcry1Ac T0 transgenic plants and their T1 progeny gave full protection from H. armigera. Although Flcry1Ac gene showed lower transformation frequency and lower expression, it showed higher toxicity to H. armigera when compared with truncated Trcry1Ac gene.
  
  
  CONCLUSIONS
  The full-length cry1Ac gene can be redesigned for higher expression and performance in dicots or a hybrid gene could be designed having a blend of strong receptor binding and stable expression characteristics for enhanced efficacy and toxicity to the susceptible insects.
authors.affiliation: Department of Biotechnology and Biosciences, Lovely Professional University (LPU), Jalandhar-Delhi G.T. Road (NH-1), Phagwara, 144411 Punjab India.
authors.forename: Bhupendra
authors.initials: B
authors.lastname: Koul
authors.affiliation: Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 UP India.
authors.forename: Reena
authors.initials: R
authors.lastname: Yadav
authors.affiliation: Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 UP India.
authors.forename: Indraneel
authors.initials: I
authors.lastname: Sanyal
authors.affiliation: Plant Transgenic Lab, CSIR-National Botanical Research Institute, Rana Pratap Marg, P.O. Box 436, Lucknow, 226 001 UP India.
authors.forename: Devindra Vijay
authors.initials: DV
authors.lastname: Amla
keywords: Agrobacterium tumefaciens; Cry1Ac toxin; Helicoverpa armigera; Insect mortality; Leaf-disc; Tomato transformation