Transient Expression Of β-Glucuronidase Gene in Transformed Shoot Tips and Calli of Cotton (Gossypium Spp)

Shoot tips of cotton cv. LD 694 (diploid) and LH 2076 (tetraploid) excised from 5–6 days old in vitro germinated seedlings were transformed following Agrobacterium and particle gun methods with the GUS gene, encoding $-glucuronidase. In addition to shoot tips, two months old hypocotyl-derived calli (LH2076) were also inoculated with Agrobacterium tumefaciens strain GV 3101 carrying tDNA with GUS gene. Three days after co-cultivation the histochemical GUS assay was done that showed GUS expression in shoot tips varid from 5.55 to 12.50 per cent and 7.14 to 13.63 per cent in calli. When shoot tips were transformed with GUS DNA coated on tungsten particle (micro-carrier) using particle gun method, its expression was up to 5.00 to 10.00 per cent. Of the two transformation methods studied, Agrobacterium-mediated gene transfer resulted in higher transformation efficiency (mean GUS expression 10.35%) than particle gun method (6.25%) in both the varieties, demonstrating Agrobacterium method as better choice for cotton transformation. Transient gene expression in shoot tip explants indicates the potential of using such explants to obtain stable transformants in Indian cotton genotypes.