Jatropha curcas L., a multipurpose oilseed plant, is very important for biodiesel production; it also has a wide range of bioactive compounds with medicinal properties and biocidal activity for control of crop pests and diseases. This review presents the state-of-the-art of the biocidal activity of J. curcas extracts. Chemical constituents such as phorbol esters are responsible for high bioactivity of J. curcas, due to their toxicity to humans and animals and to their high fungicidal and insecticidal activity. The fungicidal activity of these constituents may be due to destroy endoplasmatic reticulum and hyphae cell walls. The activity of these compounds on insect pest metabolism is well known, leading to an antifeedant effect, repellency, mating inhibition, oviposition inhibition or suppression and/or induction of infertile egg production, and inhibition of larva, nymph, and pupa development. Several studies have shown that although all organs of J. curcas plant are toxic, the degree of toxicity varies in accordance with the extract formulation, the nature of the active substance, the administration rate and procedure, and the individual sensitivity of pests and diseases. Thus, J. curcas stands out as a promising species for bioenergy purposes, as well as for control of pests and diseases that affect agriculture production.

We evaluated the genetic variability of a collection of Jatropha curcas germplasm, represented by 93 accessions, using microsatellite markers. Among the 60 markers tested, five of them detected polymorphisms, with a total of 11 alleles and mean of 2.2 alleles per loci. These five markers enabled the quantification of genetic variability through estimates of expected (He=0.42) and observed (Ho=0.64) heterozygosity, Shannon-Weaver index (H'=0.62), coefficient of inbreeding (ƒ=-0.44) and the formation of 11 clusters. Simultaneously, 14 accessions randomly sampled among the 93 and represented by seven plants each, were analyzed with these same five markers to quantify the within and between variability. Most of the genetic variation (92.58%) was contained within the accessions. These analyses revealed, for the first time, expressive genetic variability to be explored in this collection. The accessions UFVJC 05, 07, 12, 18, and 53 presented expressive variability among them with potential for the constitution of a base population for the breeding program.

J. curcas (physic nut) is one of the most promising oilseeds for biofuel production and the knowledge about genetic parameter estimates is important for its breeding. Here, we evaluated 121 families, from 48 to 60 months of age, aiming genetic evaluation and selection. The trial was set up in an 11 x 11 lattice design, with three replications and 4-plant plot. The traits evaluated were fruit yield (FY), grain (GY) and oil yield (OY), fruit husk percentage (FH) and seed oil content (OC). Individual heritabilities were low (0.19 to 0.23), requiring accurate selection and improvement methods. Moderate repeatabilities were observed for FY (0.54), GY (0.52), OC (0.30) and OY (0.51), indicating that the families evaluated maintained relative superiority over the years. With selection of the 20 best individuals, the predicted genotypic gains (66%) were greater than the additive gains (56%), indicating greater possibilities of success from cultivation of clones.

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The toxicity of J. curcas opens possibilities of breeding program on the production of extracts for controlling the plant pathogens. The H. vastatrix and C. coffeicola fungi causing leaf rust and cercosporiosis diseases, and can be responsible for up to 50% and 30% coffee yield loss, respectively. We developed a biocide for controlling the both fungi, using leaf and stem bark samples from 12 families of J. curcas and submitted them to extraction by ethanol and chloroform solvents. In assays with H. vastatrix, we used 15 µL of spore suspension and 15 µL of the J. curcas extract. Assays with C. coffeicola were performed by using isolates from coffee leaves bearing the disease, grew in PDA medium. For each family, 15 mL of PDA medium and 1 mL of the plant extract were utilized. From the third day on, the mycelial growth was assessed every 24 hours, during 13 days, by evaluating the diameter of the colonies. Data on the antifungal effect of the extracts over C. coffeicola mycelia were subjected to two-way anova. The mean testing was performed as model-identity test, as there was an over-time growth. All 12 extracts of stem bark and leaves of J. curcas, prepared with either ethanol or chloroform, proved to be efficient in controlling H. vastatrix. For C. coffeicola, the extracts inhibited partially the mycelial growth. The extracts that had ethanol as a solvent were more toxic and this result is relevant because ethanol is more accessible to the farmers and the extraction is less expensive.

J. curcas is a species with wide potential for biofuel production. However, there are few breeding programs and little information on its genetic structure. Studies indicate that the species has narrow genetic variability. We quantify genetic variability, and decomposing it within and among 28 families of a genebank by means of microsatellite markers. Thirty-nine pairs of primers were tested, of which six were polymorphic for a total of 18 alleles, with a mean of three alleles/locus. These six markers allowed genetic variability to be estimated within and among the families through estimates of PIC (0.36), expected (He=0.44) and observed (Ho=0.48) heterozygosity, inbreeding coefficient (f=-0.03), Shannon-Wiener index (H'=0.71), and the formation of 11 clusters. Bayesian analysis classified the families in four groups. The present study was the first to portray the formation of four groups and detect high genetic variability using only accessions from outside the main center of diversity of the species. Analysis of molecular variance showed that most of the variability (92.4%) is contained within families. There was low differentiation among the families (FST=0.07). Collection of genotypes within families should be prioritized because they are where greater variability is concentrated. This strategy was used in setting up the present genebank, which prioritized the collection of more plants per family, efficiently bringing together greater variability. For the first time, the diversity statistics revealed high genetic variability to be exploited in this collection, on the contrary to most studies with J. curcas that have claimed low genetic diversity in the species.