ESTs from seeds to assist the selective breeding of J. curcas L. for oil and active compounds

What is it about?

We report here on the characterization of a cDNA library from seeds of Jatropha curcas L. at three stages of fruit maturation before yellowing. We sequenced a total of 2200 clones and obtained a set of 931 non-redundant sequences (unigenes) after trimming and quality control, ie, 140 contigs and 791 singlets with PHRED quality ≥10. We found low levels of sequence redundancy and extensive metabolic coverage by homology comparison to GO. After comparison of 5841 non-redundant ESTs from a total of 13193 reads from GenBank with KEGG, we identified tags with nucleotide variations among J. curcas accessions for genes of fatty acid, terpene, alkaloid, quinone and hormone pathways of biosynthesis. More specifically, the expression level of four genes (palmitoyl-acyl carrier protein thioesterase, 3-ketoacyl-CoA thiolase B, lysophosphatidic acid acyltransferase and geranyl pyrophosphate synthase) measured by real-time PCR proved to be significantly different between leaves and fruits.

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Why is it important?

Jatropha curcas L. (Plantae; Embryophyta; Spermatopsida; Malpighiales; Euphorbiaceae) has recently drawn the attention of the international research community due to its potential as a biodiesel crop. There is an urgent need to diversify oil sources to sustain B10 (10% biodiesel) that is mandatory in Brazil since 2017. In that country, B10 is fueled mainly by soybean (80%), which is a dangerous situation for supply stability in the long term. On the other hand, there is a trend toward the increase of climate dryness in continental areas. For this reason, the availability of an industrial fuel crop well adapted to semiarid conditions would be welcome.

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