An efficient protocol for Agrobacterium-mediated transformation of the biofuel plant Jatropha curcas by optimizing kanamycin concentration and duration of delayed selection

Jatropha curcas is considered a potential biodiesel feedstock crop. Currently, the value of J. curcas is limited because its seed yield is generally low. Transgenic modification is a promising approach to improve the seed yield of J. curcas. Although Agrobacterium-mediated genetic transformation of J. curcas has been pursued for several years, the transformation efficiency remains unsatisfying. Therefore, a highly efficient and simple Agrobacterium-mediated genetic transformation method for J. curcas should be developed. We examined and optimized several key factors that affect genetic transformation of J. curcas in this study. The results showed that the EHA105 strain was superior to the other three Agrobacterium tumefaciens strains for infecting J. curcas cotyledons, and the supplementation of 100 mM acetosyringone slightly increased the transient transformation frequency. Use of the appropriate inoculation method, optimal kanamycin concentration and appropriate duration of delayed selection also improved the efficiency of stable genetic transformation of J. curcas. The percentage of β-glucuronidase positive J. curcas shoots reached as high as 56.0 %, and 1.70 transformants per explant were obtained with this protocol. Furthermore, we optimized the root-inducing medium to achieve a rooting rate of 84.9 %. Stable integration of the T-DNA into the genomes of putative transgenic lines was confirmed by PCR and Southern blot analysis. Using this improved protocol, a large number of transgenic J. curcas plantlets can be routinely obtained within approximately 4 months. The detailed information provided here for each step of J. curcas transformation should enable successful implementation of this transgenic technology in other laboratories. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11816-015-0377-0) contains supplementary material, which is available to authorized users.