Investigation of genetic variation in Jatropha curcas by Ecotilling and ISSR

Background The ability of species to adapt to different environments resides in their genetic diversity. This diversity, most commonly manifested as Single Nucleotide Polymorphisms (SNPs), can provide clues to the adaptive processes and population histories that have played a role in the species’ evolution. A number of different techniques for identifying SNPs have been developed, all having their limitations. Reverse genetics approaches rely on the detection of sequence alterations in target genes to identify allelic variations in natural or mutant populations. Ecotilling, a variant of TILLING (Targeting Induced Local Lesions IN Genomes) technique, allows high-throughput analyses of natural genetic diversity in plants [1], particularly in species with limited genetic diversity. Jatropha curcas L. is a perennial, monoecious shrub of the Euphorbiaceae family, native to America but distributed widely in the tropical and subtropical areas [2]. Wild or semi-cultivated types of J. curcas can grow well under unfavourable climatic and soil conditions [3]. J. curcas has attracted a great deal of attention worldwide, regarding its potential as a new energy plant. The seeds of J. curcas contain 30-45% oil [4] with a high percentage of monounsaturated oleic and polyunsaturated linoleic acid [5]. For genomic analyses, J. curcas is an interesting model species, since it has a relatively small genome (2C DNA content of 0.850 ± 0.006 pg or C DNA content of 0.416 × 109 bp) [6]. However, to achieve specific breeding goals in Jatropha for wider ecological adaptation, disease resistance and novel seed quality, the use of germplasm from different group and regions is necessary. Understanding the population structure of the alternative bioenergy plant Jatropha curcas is challenging due to limited genetic variability and information on phylogenetic relationships between accessions and related species. The development of cultivars of Jatropha curcas by conventional breeding will profit largely from biotechnological support (pathogen-free accessions with specific traits, non-toxic, high yielding varieties). The knowledge about J. curcas remains limited and little genomic research has been done so far [7]. In fact, the genetic map of J. curcas is not well-developed and only few molecular markers exist that could be used to clearly distinguish world wide accessions. Therefore, a resource database of SNPs in J. curcas would provide researchers with a tool for answering questions concerning population structure or adaptation and allow comparison of this species with related species.