Molecular Markers Reveal Limited Genetic Diversity in a Large Germplasm Collection of the Biofuel Crop Jatropha curcas L. in Brazil

Abstract

The genetic diversity of a comprehensive germplasm collection involving 192 Jatropha curcas L. accessions collected throughout Brazil, spanning a wide latitudinal range from the states of Maranhão (1°49′ S, 44°52′ W) to Rio Grande do Sul (29°33′ S, 55°07′ W), was studied with 96 random amplified polymorphic DNA (RAPD) primers and six selected microsatellite markers. Only 23 of the 381 replicated RAPD markers and one microsatellite were polymorphic. Surprisingly, all accessions were homozygous at all but one microsatellite, in contrast with the outcrossing mating system reported for the species, suggesting that J. curcas not only supports selfing but possibly breeds by geitonogamy. Similarity based clustering revealed only 43 unique multilocus profiles in the 192 accessions. The probabilities of accessions with indistinguishable multilocus profiles being true duplicates varied between 83 and 99%. No relationship between clustering of accessions and geographic origin was observed, suggesting that J. curcas has experienced a widespread dispersion across regions by seeds and possibly vegetative propagules. The narrow genetic base and extent of potentially duplicated accessions likely reflects a recent common ancestry, drift, and intensive selection of the currently cultivated materials since the time of introduction. This result highlights an urgent need for the introduction of new and diverse accessions to this germplasm collection if Brazil is to drive and sustain successful breeding programs.

Genetic gains in physic nut using selection indexes

“…Since significant variability between families is essential for genetic progress, the variables NSF, E/S, TNB 0.5 , and TNB 1.0 were not used in the estimations of genetic gain. The estimated genetic variability for the components of production, in the present study, does not agree with the low genetic diversity quantified using molecular markers on the physic nut collection worldwide (Achten et al, 2010;Rosado et al, 2010). This may be related to a possible dissociation of the neutral molecular markers used in these studies with the genes that control production traits.…”

Adaptabilidade e estabilidade de progênies de meios-irmãos de pinhão-manso em diferentes regiões do Brasil

“…Apesar da baixa diversidade genética quantificada por técnicas de marcadores moleculares (Rosado et al, 2010), avaliações agronômicas têm mostrado variabilidade genética para os principais componentes da produção dessa oleaginosa (Mishra et al, 2009 Ainda considerada em fase de domesticação, a viabilidade deste cultivo ainda depende de um incremento de produtividade, a ser realizado com a seleção de plantas e melhoria das condições de ambiente (Drumond et al, 2010;Gouveia et al, 2012;Laviola et al 2012). As novas médias estimadas com o plantio das progênies selecionadas, em toneladas por hectare, foram de 2,34 ton.ha , em Pelotas -RS.…”

Analysis of morpho-agronomic and climatic variables in successive agricultural years provides novel information regarding the phenological cycle of Jatropha in conditions of the Brazilian cerrado

“…Several studies have been carried out in order to domesticate it. Results of these studies (Bhering et al 2013, Bhering et al 2013, Rocha et al 2012, 2011a, b, 2012a, b, Rosado et al 2010, Spinelli et al 2010, Juhász et al 2009) confirm that the species has a high potential to be exploited commercially. Parallel to this work, attempts to introduce this species in various regions in Brazil are being carried out, such as in the Cerrado (a savannah-like biome) and in the semiarid regions.…”

“…The evaluated variables were correlated with climatic variables by means of the Pearson correlation coefficient. All analyses were performed using Genes software , Cruz 2006a, b, 2010, Cruz et al 2004.…”