Linkage mapping in the oilseed crop Jatropha curcas L. reveals a locus controlling the biosynthesis of phorbol esters which cause seed toxicity

Abstract

Current efforts to grow the tropical oilseed crop Jatropha curcas L. economically are hampered by the lack of cultivars and the presence of toxic phorbol esters (PE) within the seeds of most provenances. These PE restrict the conversion of seed cake into animal feed, although naturally occurring ‘nontoxic’ provenances exist which produce seed lacking PE. As an important step towards the development of genetically improved varieties of J. curcas, we constructed a linkage map from four F2 mapping populations. The consensus linkage map contains 502 codominant markers, distributed over 11 linkage groups, with a mean marker density of 1.8 cM per unique locus. Analysis of the inheritance of PE biosynthesis indicated that this is a maternally controlled dominant monogenic trait. This maternal control is due to biosynthesis of the PE occurring only within maternal tissues. The trait segregated 3 : 1 within seeds collected from F2 plants, and QTL analysis revealed that a locus on linkage group 8 was responsible for phorbol ester biosynthesis. By taking advantage of the draft genome assemblies of J. curcas and Ricinus communis (castor), a comparative mapping approach was used to develop additional markers to fine map this mutation within 2.3 cM. The linkage map provides a framework for the dissection of agronomic traits in J. curcas, and the development of improved varieties by marker-assisted breeding. The identification of the locus responsible for PE biosynthesis means that it is now possible to rapidly breed new nontoxic varieties.

Production of Bioactive Diterpenoids in the Euphorbiaceae Depends on Evolutionarily Conserved Gene Clusters

“…We also mapped a previously described BAC sequence (GenBank accession AP011970; Sato et al, 2011) to this region, which contains both a casbene synthase and CYP726A pseudogenes. Interestingly, the putative gene cluster in J. curcas is on a separate linkage group to a locus that we have previously identified as being responsible for the loss of phorbol ester biosynthesis in the seed of some naturally occurring provenances of this species (King et al, 2013). However, we observed that varieties of J. curcas that do not produce phorbol esters within seeds are not compromised in their ability to produce diterpenoids within roots, indicating that diterpenoid biosynthesis per se is not blocked in these plants.…”

“…Using heterologous gene expression in E. coli, we confirmed that all three of these genes were casbene synthases (Supplemental Figure 7). Using an F2 mapping population we have described previously (King et al, 2013), we were also able to map sequences corresponding to two CYP726A genes and the three casbene synthase genes to a single locus on chromosome 1 ( Figure 5A). We also mapped a previously described BAC sequence (GenBank accession AP011970; Sato et al, 2011) to this region, which contains both a casbene synthase and CYP726A pseudogenes.…”

“…Linkage mapping was performed in a mapping population described previously (King et al, 2013), using either simple sequence repeat markers or single nucleotide polymorphism markers detailed in Supplemental Table 5. The genetic linkage map was constructed using CRI-MAP software (www.animalgenome.org).…”

Economic and Social Sustainability Performance of Jatropha Projects: Results from Field Surveys in Mozambique, Tanzania and Mali

“…This may change in the future when more reliable and better yielding varieties become available, or when fossil oil prices rise again. Given current plant breeding efforts, agronomic advances could come in a matter of years rather than decades, see e.g., [24,25], but it still remains an open question under what conditions smallholder farmers would be able to gain access to these (presumably patented) improved varieties, and whether resource-poor smallholders could furnish the kind of cultivation regime that these varieties would demand in order to flourish.  For plantations, the current financial outlook is also poor: upfront investments are very high while returns are uncertain and slow to arrive.…”

Pendekatan Bioteknologi dan Genomika untuk Perbaikan Genetik Tanaman Jarak Pagar sebagai Penghasil Bahan Bakar Nabati

“…Peta genetik ini merupakan fondasi penting untuk pemetaan gen dan QTL dari karakter agronomis penting, pemuliaan berbantuan marka, dan memfasilitasi usaha kloning gen dan QTL yang bertanggung jawab terhadap fenotipe karakter unggul jarak pagar. King et al (2013) mempublikasikan peta genetik jarak pagar berikutnya yang didasarkan pada empat populasi interspesifik J. curcas  J. integerrima. Peta pautan genetik yang dihasilkan pada populasi masing-masing diintegrasikan menjadi satu peta genetik menggunakan software JoinMap® untuk menghasilkan peta genetik gabungan dengan panjang jarak genetik 717,0 cM dengan rerata jarak genetik antara dua marka yang berdampingan sebesar 1,5 cM (King et al 2013).…”