Agrobacterium mediated genetic transformation of commercial jute cultivar Corchorus capsularis cv. JRC 321 using shoot tip explants

Abstract

We have developed a reproducible method of Agrobacterium tumefaciens mediated stable genetic transformation of white jute (Corchorus capsularis cv. JRC 321) utilizing the shoot organogenesis potential of the shoot tip apical meristem. A. tumefaciens strain LBA4404 harboring the binary vector pCAMBIA 1301 was used in the transformation experiments. The explants were subjected to varying durations of preculture and cocultivation with A. tumefaciens in the presence of acetosyringone in order to optimize the conditions conducive for the highest expression of transgene. A schedule of 1 day preculture of shoot tips followed by 3 days cocultivation was optimized for Agrobacterium mediated stable genetic transformation of C. capsularis cv. JRC 321. The optimized lethal doses of the antibiotic hygromycin B for shoot tips (12 mg/L) and for 5 days old seedlings (14 mg/L) were employed in efficient selection of the transformed tissues. This method of transformation resulted in a mean transformation efficiency of 4.09 %. Stable expression of the intron harbored gusA transgene was observed in mature organs of the transformed plants and their progenies. Genomic integration and inheritance of the hpt transgene was further confirmed by Southern blot analysis. The transformed plants exhibited normal morphology and most of them produced viable progenies, many of which segregated in a 3:1 ratio following Mendelian inheritance for a single dominant locus. However, strong P value support for 3:1 segregation ratio was obtained in case of two lines of independent transformants. Nevertheless, the method of transformation mentioned in this protocol could be effectively implemented in genetic transformation of many other cultivars of jute due to the genotype independent regeneration potential of the shoot tip explants.