Jatropha curcas is a potential energy crop and has been identified as a significant resource for biodiesel. Retrotransposons occupy the plant genome in a large proportion, so the specific retrotransposon characterization will help improve understanding of the Jatropha genome evolution and organization. This research aimed to characterize and classify Ty1-copia retrotransposons in J. curcas using specific gene sequence and to detect the distribution of Ty1-copia in J. curcas and J. integerrima chromosomes using florescence in situ hybridization (FISH) method. Ty1-copia sequences from J. curcas were isolated using three degenerate primer sets specific to the conserved Ty1-copia reverse transcriptase gene for polymerase chain reaction (PCR). FISH technique using the Ty1-copia probes was used to map physically on J. curcas and J. integerrima chromosomes. Altogether, 164 Ty1-copia sequences were obtained to use for the phylogenetic analysis and were classified into the four families of TAR, Angela, Ale and Bianca. Physical map using FISH method of Angela and Ale families on J. curcas and J. integerrima chromosomes exhibited biases for specific regions around the centromeres or at the chromosome terminal regions. The study indicates the high variation of the Ty1-copia elements in the genome of Jatropha. These results will enhance understanding of retrotransposon chromosomal distribution and evolution of the J. curcas genome and also promotion of retrotransposon possible utilization in J. curcas improvement projects using retrotransposon-based markers.

The structural transitions RNAs undergo during trafficking are not well-understood. Here, we used the well-developed yeast Ty1 retrotransposon to provide the first structural model of genome (g) RNA in the nucleus from a retrovirus-like transposon. Through a detailed comparison of nuclear Ty1 gRNA structure with those established in the cytoplasm, virus-like particles (VLPs), and synthesized in vitro, we detected Ty1 gRNA structural alternations that occur during retrotransposition. Full-length Ty1 gRNA serves as the mRNA for Gag and Gag-Pol proteins and as the genome that is reverse transcribed within VLPs. We show that about 60% of base pairs predicted for the nuclear Ty1 gRNA appear in the cytoplasm, and active translation does not account for such structural differences. Most of the shared base pairs are represented by short-range interactions, while the long-distance pairings seem unique for each compartment. Highly structured motifs tend to be preserved after nuclear export of Ty1 gRNA. In addition, our study highlights the important role of Ty1 Gag in mediating critical RNA:RNA interactions required for retrotransposition.