Cotton, the major cash crop in Pakistan, suffers 30% losses to cotton leaf curl disease, caused by the geminivirus, cotton leaf curl virus DNA A, plus a satellite component, DNA beta responsible for symptom development with plants failing to produce cotton bolls. We constructed transgenic tobacco expressing sense and antisense RNAs representing: [i] the 5' half of the viral DNA replication gene, AC1, [ii] the 3' half of AC1, [iii] two overlapping genes, AC2, a transcription activator, and AC3, a replication enhancer. In contrast to controls, 25% of 72 transgenic tobacco lines tested showed heritable resistance [T(1) - T(3) generations]: symptom-free and no replication of DNA A or DNA beta even after 120 days of continuous exposure to viruliferous whiteflies. As geminiviral and transgene RNAs are not detected in resistant lines following infection, and selected uninfected resistant tobacco sense lines reveal double-stranded and small interfering RNAs, the most likely mechanism is via post-transcriptional gene silencing.

A combination of two techniques i.e. particle bombardment and Agrobacterium method was applied to transfer marker NPT-ll and insecticidal cry1A(b) gene into zygotic embryos of cotton variety MNH-93. Wounding in embryos produced by bombardment of tungsten particles increased the efficiency of Agrobacterium mediated transformation. Primary transformants selected on selection medium containing Kanamycin (100 µg/ml) for 6-8 week showed the presence and expression of cry1A(b) gene in the primary transformants. Insect Bioassays with 2nd instar larvae of of American bollworm (Heliothis armigera), PCR amplification,of the coding region of cry1A(b) gene in plant gennnle and ELISA with the antibodies against cryt1A(c) con . firmed the transformation.