Improvement of sugarcane for borer resistance using Agrobacterium mediated transformation of cry1Ac gene.

The sugarcane (Saccharum X officinarum) is one of the most important crops used to produce sugar and raw material for biofuel in the world. One of the main causes for sucrose content and yield losses is the attack by insect. In this investigation, cry1Ac gene was introduced into sugarcane variety GT54-9(C9) using the Agrobacterium tumefaciens transformation method for transgenic sugarcane production presenting insect-resistance. The A. tumefaciens strain GV1303 including pARTcry1Ac vector was used for the production of transformed sugarcane. The Bacillus thuringiensis cry gene were successfully used to produce transgenic plants used for the improvement of both agronomic efficiency and product quality by acquiring insect resistance. PCR and Southern hybridization techniques were used to confirm the cry1Ac gene incorporation into sugarcane genome. Transformation percentage was 22.2% using PCR analysis with specific primers for cry1Ac and npt-II (Neomycin phosphotransferase) genes. The expression of cry1Ac gene was determined using reverse transcriptase polymerase chain reaction (RT-PCR), QuickStix test, and insect bioassays. Bioassays for transformed sugarcane plants showed high level of toxicity to Sesamia cretica giving 100% mortality of the larvae. Sugarcane insect resistance was improved significantly by using cry1Ac gene transformation.

Evaluation of genetically modified sugarcane lines carrying Cry 1AC gene using molecular marker techniques.

Five genetically modified insect resistant sugarcane lines harboring the Bt Cry 1AC gene to produce insecticidal proteins were compared with non-transgenic control by using three types of molecular marker techniques namely, RAPD, ISSR and AFLP. These techniques were applied on transgenic and non-transgenic plants to investigate the genetic variations, which may appear in sugarcane clones. This variation might demonstrate the genomic changes associated with the transformation process, which could change important molecular basis of various biological phenomena. Genetic variations were screened using 22 different RAPD primers, 10 ISSR primers and 13 AFLP primer combinations. Analysis of RAPD and ISSR banding patterns gave no exclusive evidence for genetic variations. Meanwhile, the percentage of polymorphic bands was 0.45% in each of RAPD and ISSR, while the polymorphism generated by AFLP analysis was 1.8%. The maximum percentage of polymorphic bands was 1.4%, 1.1% and 5.5% in RAPD, ISSR and AFLP, respectively. These results demonstrate that most transgenic lines showed genomic homogeneity and verified minor genomic changes. Dendrograms revealing the relationships among the transgenic and control plants were developed from the data of each of the three marker types.

In vitro root induction of faba bean (Vicia faba L.).

A major challenge for regeneration of faba bean (Vicia faba L.) plants is the difficulty of in vitro root induction. In the present study, in vitro rooting and its architecture have been studied. Adventitious root formation was successfully induced from regenerated faba bean shoots of four Egyptian cultivars, i.e., Giza 461, Giza 40, Giza 834 and Giza 716 on hormone free MS medium supplemented with 5 mg/l silver nitrate. Among the four cultivars, Giza 461 and Giza 40 were recorded as the highest root formation response (75 % and 65) followed by cultivars Giza716 and Giza843 (20%, and 10%). Anatomical study proved that the produced roots are initiated as the adventitious lateral root (LR) with tri-arch xylem strands as compared with the penta-arch of the primary roots of the intact faba bean seedling. The obtained results overcome the root induction problem in faba bean.

Establishment of regeneration and transformation system of sugarcane cultivar GT54-9 (C9).

Plant regeneration protocols for sugarcane GT54-9(C9) cultivar were developed for direct organogenesis and indirect somatic embryogenesis, using young leaf segments as explants by studying the influence of different concentrations and types of cytokinin and auxin hormones. For the callus formation from young leaves, a medium containing 4mg/l 2,4-D was found very effective. For embryo formation, MS medium supplemented with 1mg/l Kin and 0.5 mg/l 2,4-D was used. While in the case of direct organogenesis protocol, the medium containing 1mg/l BAP and 2mg/l NAA was the best for direct shoot formation. Data showed that the best shoot regeneration and elongation medium for direct organogenesis and indirect somatic embryogenesis was obtained on medium with 2 mg/l Kin and 0.1 mg/l BAP. Root induction was best performed on 2mg/l NAA and complete plantlets were hardened in the greenhouse before transferring to the field for further evaluation. For transformation, young leaf segments of sugarcane from the cultivar GT54-9(C9) were inoculated and co-cultivated with Agrobacterium tumefaciens strain LB4404 harboring the binary vector pISV2678 with the bar and the gus-intron genes. The obtained putative transgenic plantlets were able to grow under bialaphose containing medium. Stable integration of the bar gene into the plant genomes was tested by PCR and Southern blot hybridization. Histochemical assay and leaf painting analysis were carried out to study the expression of the gus and bar genes in transgenic plants, respectively. The results indicated that the direct organogenesis produced a higher yield of regenerated plants (22% more) within shorter time (4 weeks less). Therefore, this method is recommended for sugarcane regeneration and for further use in genetic transformation via A. tumefaciens with desired genes.