Edible Jatropha: SNPs Linked to Non-Toxic Trait Identified to Support Molecular Breeding

Jatropha curcas L. has recently gained commercial interest because of its ability to produce oil suitable as fuel and its tolerance to marginal soil and dry climate conditions. However the jatropha accessions grown world-wide produce phorbol esters (PE) that are highly toxic for animals. The seed kernel cake by-product that is obtained after oil extraction has a very high protein content (>60% on dry matter) with a favorable amino acids composition, but it contains high level of PE that makes it inedible to animals and humans. One of the main objectives of Jatropower AG (www.jatropower.ch), a Swiss breeding company fully dedicated at the improvement of J. curcas, is to develop varieties lacking PE compounds by introgressing the Non-Toxicity (NT) trait from wild germplasm accessions into elite varieties. This project identified SNPs linked to the NT gene(s) by high-throughput genotyping-by-sequencing of a F₂ population using bulked-segregant-analysis. A total of 6,248 homozygous SNPs with different alleles between parents were identified, of which 83 differentially segregated between bulks. Alignment of these SNP sequences to the J. curcas reference genome showed co-localization of these putatively NT-linked SNPs on a 10 Mbp region of chromosome 8. Based on the results of its research, Jatropower AG has recently started the commercial production of its non-toxic germplasm varieties and it is now the first company to offer elite edible jatropha varieties to the market. Identification of SNPs linked to the NT gene(s) will strengthen the efforts towards further improving the non-toxic jatropha crop through hybridization.