Diversity and genetic parameter estimates for yield and its components in Jatropha curcas L.

Jatropha curcas L. is one of the most promising oilseeds for biodiesel and biokerosene production, but few basic studies or breeding programs have been conducted for the species. We estimated genetic parameters and diversity based on 10 yield traits in 77 half-sib progenies of J. curcas after 52 months in the field, and evaluated correlations between them and the oil content of the seeds. The mean grain yield per plant was 377.9 g (ranging from 169.8 to 772.1 g) and the mean oil content was 36.2% (ranging from 30 to 39.6%). Moderate estimates of heritability at the mean progeny level were obtained for the length of the fruit (84.7%), length (69.1%) and width (68.2%) of the seed, and grain yield per plant (62.2%). Oil content was only positively and significantly correlated with 100-seed weight. Our study revealed a range of possible crosses to be investigated in J. curcas. Progeny production should be evaluated over several crop seasons for the accurate selection of the best progenies.

Genetic diversity of gabiroba based on random amplified polymorphic DNA markers and morphological characteristics.

The fragmentation of the original vegetation of the Cerrado biome, caused by the expansion of agricultural areas, mainly in central-west Brazil, calls for an assessment of the native population of this vegetation, especially of the species of interest for domestication and sustainable use. The purpose of this study was to characterize the genetic diversity of 140 gabiroba mother plants (Campomanesia spp) and their progenies from 17 locations in Goiás. The morphological characteristics of the mother plants were evaluated, and the leaflets were collected for molecular analysis using 12 random amplified polymorphic DNA primers. The seed progenies of these matrices were transplanted to the field and morphologically evaluated. Distance matrices of the morphological data of the mother plants and progenies as well as the molecular data of the mother plants were constructed, and groups were formed using the Tocher method and the unweighted pair-group method based on arithmetic averages. The polymorphism level in the matrix was 90.44%. The greatest molecular distance (0.66) was observed between mother plants from Santa Rita do Araguaia and Alexânia. By the Tocher method, 10, 13, and 17 groups were formed. The morphological evaluation of the mother plants and progenies as well as the molecular analysis of the mother plants showed genetic diversity. Significant genetic variability was detected in the progenies of the gabiroba base collection planted in Campus Jataí, Goiás.

Antiquity, botany, origin and domestication of Jatropha curcas (Euphorbiaceae), a plant species with potential for biodiesel production.

Jatropha curcas is a multi-purpose plant species, with many advantages for biodiesel production. Its potential oil productivity is 1.9 t/ha, beginning the fourth year after planting. Nevertheless, limitations such as high harvest cost, lack of scientific konowledge and low profitability have prevented it from being utilized commercially. In order to provide information that could be useful to improve the status of this species as a bioenergy plant, we elucidated the center of origin and the center of domestication of J. curcas (Mexico). Evidence of the antiquity of knowledge of J. curcas by Olmeca people, who lived 3500-5000 years ago, reinforces its Mexican origin. The existence of non-toxic types, which only exist in that country, along with DNA studies, also strongly suggest that Mexico is the domestication center of this species. In Brazil, the Northern region of Minas Gerais State presents types with the highest oil content. Here we propose this region as a secondary center of diversity of J. curcas.

Relative h-index to compare the scientific performance of researchers.

I propose the Relative h-index of a scientist, which is based on his or her Hirsch's h-index divided by the total number of published papers recorded in the database. The Relative index h allows for a comparison of the scientific output among researchers and can be very useful for research support institutions, universities, and institutes to rank researchers for the purposes of recruitment, promotions, awards, and grant funding for projects.

Genetic characterization of an elite coffee germplasm assessed by gSSR and EST-SSR markers.

Coffee is one of the main agrifood commodities traded worldwide. In 2009, coffee accounted for 6.1% of the value of Brazilian agricultural production, generating a revenue of US$6 billion. Despite the importance of coffee production in Brazil, it is supported by a narrow genetic base, with few accessions. Molecular differentiation and diversity of a coffee breeding program were assessed with gSSR and EST-SSR markers. The study comprised 24 coffee accessions according to their genetic origin: arabica accessions (six traditional genotypes of C. arabica), resistant arabica (six leaf rust-resistant C. arabica genotypes with introgression of Híbrido de Timor), robusta (five C. canephora genotypes), Híbrido de Timor (three C. arabica x C. canephora), triploids (three C. arabica x C. racemosa), and racemosa (one C. racemosa). Allele and polymorphism analysis, AMOVA, the Student t-test, Jaccard's dissimilarity coefficient, cluster analysis, correlation of genetic distances, and discriminant analysis, were performed. EST-SSR markers gave 25 exclusive alleles per genetic group, while gSSR showed 47, which will be useful for differentiating accessions and for fingerprinting varieties. The gSSR markers detected a higher percentage of polymorphism among (35% higher on average) and within (42.9% higher on average) the genetic groups, compared to EST-SSR markers. The highest percentage of polymorphism within the genetic groups was found with gSSR markers for robusta (89.2%) and for resistant arabica (39.5%). It was possible to differentiate all genotypes including the arabica-related accessions. Nevertheless, combined use of gSSR and EST-SSR markers is recommended for coffee molecular characterization, because EST-SSRs can provide complementary information.

Genetic evaluation of Jatropha curcas: an important oilseed for biodiesel production.

Jatropha curcas, internationally and locally known, respectively, as physic nut and pinhão manso, is a highly promising species for biodiesel production in Brazil and other countries in the tropics. It is rustic, grows in warm regions and is easily cultivated. These characteristics and high-quality oil yields from the seeds have made this plant a priority for biodiesel programs in Brazil. Consequently, this species merits genetic investigations aimed at improving yields. Some studies have detected genetic variability in accessions in Africa and Asia. We have made the first genetic evaluation of J. curcas collected from Brazil. Our objective was to quantify genetic diversity and to estimate genetic parameters for growth and production traits and seed oil content. We evaluated 75 J. curcas progenies collected from Brazil and three from Cambodia. The mean oil content in the seeds was 31%, ranging from 16 to 45%. No genetic correlation between growth traits and seed oil content was found. However, high coefficients of genetic variation were found for plant height, number of branches, height of branches, and stem diameter. The highest individual narrow-sense heritabilities were found for leaf length (0.35) and width (0.34), stem diameter (0.24) and height of branches (0.21). We used a clustering algorithm to genetically identify the closest and most distant progenies, to assist in the development of new cultivars. Geographical diversity did not necessarily represent the genetic diversity among the accessions collected. These results are important for the continuity of breeding programs, aimed at obtaining cultivars with high grain yield and high oil content in seeds.