**Author details**

varied from 0.1 to 0.5% of total soluble protein. These levels were enough to induce a protective systemic antibody response in mice. In another attempt, capsid precursor polypeptide (P1) was expressed in rice, and 0.6–1.3 mg/g of TSP was observed that induced a protective immune response in mice [53]. Further, in mice when vaccinated orally, FMDV-specific mucosal immune responses were detected. However, partial virus clearance after challenge was observed. To address these low-expression problems, chloroplast transformation approach can be used. In a study, VP1 was expressed in tobacco chloroplasts and 2–3% values were recorded [54]. In another study, epitopes (B cell) of structural proteins VP1 and VP4 and of nonstructural proteins 2C and 3D (T cell) were produced in *N. benthamiana* plants using a plant virus expression system [55]. More recently, tandem-linked VP1 proteins of two serotypes, A and O, are expressed in forage crop *Crotalaria juncea* and fed to guinea pigs that produced humoral as well as cell-mediated immune responses [56]. From all these studies and experiments being carried out in the laboratory of the author of this chapter demonstrate that plant-based overexpression of antigenic proteins to control FMDV is an effective way but needs further experimentation to improve efficacy of edible vaccines by engineering epitopic

Nuclear transformation, achieved using microprojectile bombardment or *Agrobacterium* strains, is predominantly carried out to tailor agronomic traits in crops. However, this technology is not successful to transform upland cotton where cells are recalcitrant to regeneration, despite genome mixing through crosses between different genotypes. Biotechnologists rely on this technology though genes escape and pollinate other related crops or weeds, developing weeds or super weeds, respectively. An alternate strategy to develop transgenics is the chloroplast transformation technology since this technology offers natural gene containment, highlevel transgene expression with bona fide structures of proteins, and allows all transformation events to be uniform as far as gene integration into the plastome is concerned. High-level gene expression is due to the polyploid nature of chloroplasts in a cell and of plastomes in each chloroplast, biologically active proteins are due to the presence of chaperon proteins, and uniform integration of transgenes into the plastome is due to the homologous recombination. Hence, chloroplast transformation is more suitable for expression of health-related traits in plants rather agronomic in crops. In either case, transgenics should be grown in the field fol-

The corresponding author would like to acknowledge Punjab Agricultural Research Board (PARB) and Higher Education Commission (HEC) for providing funds to MSK for

proteins with different adjuvants (Khan MS, unpublished).

10 Transgenic Crops - Emerging Trends and Future Perspectives

lowing approved biosafety guidelines and strict stewardship.

**5. Conclusions**

**Acknowledgements**

research.

Muhammad Sarwar Khan<sup>1</sup> \* and Kauser Abdulla Malik<sup>2</sup>

\*Address all correspondence to: sarwarkhan\_40@hotmail.com

1 Center of Agricultural Biochemistry and Biotechnology (CABB), University of Agriculture, Faisalabad, Pakistan

2 Forman Christian College (A chartered University), Lahore, Pakistan
