Genome size, base composition and karyotype of Jatropha curcas L., an important biofuel plant

In this report, we present the genome size, the base composition and the karyotype of Jatropha curcas L., which is becoming an important oleaginous crop in tropical areas for biofuel production. The genome size and the base composition were obtained by flow cytometry of G0/G1 nuclei stained with propidium iodide (for genome size), DAPI (for AT) and chromomycin A3 (for GC), respectively. The karyotype was obtained by root-tip (i) incubation with amiprophos-methyl (microtubule inhibitor), (ii) digestion in enzymatic solution, (iii) squashing on glass slides, (iv) fixation and (v) coloration in Giemsa solution. We found that the genome of J. curcas is relatively small and in the same size range as that of rice. The flow cytometry indicates an average 2C value of 0.85 pg and an average base composition of 38.7% GC. The karyotype of J. curcas is made up of 22 relatively small metacentric and submetacentric chromosomes whose size range from 1.71 to 1.24 μm. The possibility of a polyploidization event in the evolutionary history of J. curcas is discussed.