Effects associated with insertion of cryptogein gene utilizing Ri and Ti plasmids on morphology and secondary metabolites are stable in Bacopa monnieri-transformed plants grown in vitro and ex vitro

Bacopa monnieri (Linn.) Wettst. (family Scrophulariaceae), a therapeutically important perennial herb, was transformed to study the stability of the effects associated with the insertion of a gene encoding β-cryptogein, a proteinaceous elicitor, either alone or in addition to the T-DNA genes in long-term in vitro culture as well as after transfer to the greenhouse. Plant lines BmAr-IXcrypt obtained via transformation by LBA 9402-crypt (pRi1855+pBin19++crypt) showed integration and expression of rolA, rolB, rolC, and rolD genes after 4 years of maintenance in vitro. The plant line BmAt-ncrypt obtained via transformation with A. tumefaciens strain LBA4404-crypt (harboring pBin19++crypt) as well as plant line BmAr-IXcrypt showed stable integration and expression of nptII gene and crypt gene even after transfer to greenhouse. The clones of Ri-crypt-transformed plants differed morphologically from Ri-transformed plants in that the typical “hairy root syndrome” was not observed in plants expressing crypt gene in the presence of rol genes. Except plant line BmAr-IXcrypt, none of the other transgenic plant lines showed any alteration in floral morphology and onset of flowering. The crypt-transformed plant lines (BmAr-IXcrypt and BmAt-ncrypt), maintained under long-term culture, showed significantly higher (p ≤ 0.05) amount of bacoside production in vitro (1.66- to 2.05-fold, with respect to non-transformed plants). In addition, accumulation of all the four bacosides was significantly higher (p ≤ 0.05) in crypt-transformed plants as compared to non-transformed plants grown for 1 year in greenhouse. Thus, the crypt-transformed plant lines of B. monnieri may be considered as the potential source for sustainable bioproduction of bacosides.