Jatropha curcas L. has become an important source of oil production for biodiesel fuel. Most genetic studies of this plant have been conducted with Asian and African accessions, where low diversity was encountered. There are no studies of this kind focusing in the postulated region of origin. Therefore, five populations of J. curcas were studied in the state of Chiapas, Mexico, using amplified fragment length polymorphism (AFLP) markers. One hundred and fifty-two useful markers were obtained: overall polymorphism = 81.18% and overall Nei’s genetic diversity (He) = 0.192. The most diverse population was the Border population [He: 0.245, Shanon’s information index (I): 0.378]. A cluster analysis revealed the highest dissimilarity coefficient (0.893) yet to be reported among accessions. An analysis of molecular variance (AMOVA) revealed that the greatest variation is within populations (87.8%), followed by the variation among populations (7.88%). The PhiST value (0.121) indicated moderate differentiation between populations. However, a spatial AMOVA (SAMOVA) detected a stronger genetic structure of populations, with a PhiST value of 0.176. To understand the fine structure of populations, an analysis of data with Bayesian statistics was conducted with software Structure^©. The number of genetic populations (K) was five, with mixed ancestry in most individuals (genetic migrants), except in the Soconusco, where there was a tiny fraction of fragments from other populations. In contrast, SAMOVA grouped populations in four units. To corroborate the above findings, we searched for possible genetic barriers, determining as the main barrier that separating the Border from the rest of the populations. The results are discussed based on the possible ancestry of populations.

Various government agencies around the world have proposed vegetable oils and their conversion to biodiesel as a renewable alternative to fossil fuels. Due to its adaptability to marginal soils and environments, the cultivation of Jatropha curcas is frequently mentioned as the best option for producing biodiesel. In the present work the current situation of proven and potential reserves of fossil fuel, and the production and consumption model for the same are analyzed, in order to later review the sustainability of the production process which begins with the cultivation of J. curcas, and culminates with the consumption of biodiesel. A review of the following topics is proposed in order to improve the sustainability of the process: areas destined for cultivation, use of external (chemical) inputs in cultivation, processes for converting the vegetable oil to biodiesel, and, above all, the location for ultimate consumption of the biofuel.

La antracnosis y pudrición blanda en frutos de papaya provocan deterioro de la calidad, así como grandes pérdidas durante el manejo postcosecha. El uso de estrategias individuales para el control de enfermedades resulta poco eficiente. Por lo anterior, en el presente estudio se evaluó el efecto sinérgico de varias estrategias de control sobre la incidencia de enfermedad causada por la inoculación de esporas de los hongos Colletotrichum gloeosporioides (Penz.) y Rhizopus stolonifer (Ehrenb.) en papaya var. Maradol. Se evaluaron tratamientos resultantes de la combinación del uso de biorecubrimientos compuestos elaborados con quitosán (15 g L-1) adicionadas con aceites esenciales (AE) de clavo, tomillo y/o lima (5 ó 10 mL L-1 de cada AE) y tres dosis de irradiación UV-C (0.97 kJ·m-2, 2 kJ·m-2 y 2.88 kJ·m-2), aplicados a las 12, 24 y 48 h post-inoculación de esporas de los fitopatógenos. El tratamiento donde se combinó el biorecubrimiento adicionado con 10 mL L-1 de AE de clavo y 10 mL L-1 de AE de tomillo y una dosis de irradiación UV-C de 2.88 kJ m-2 (B1T92) aplicado a las 24 h post-inoculación de esporas, logró mantener la incidencia de enfermedad (para ambos hongos evaluados) a valores menores de 25% durante nueve días de almacenamiento a temperatura de 28 ± 3 °C y 80% de HR. Este mismo tratamiento redujo la velocidad específica de la enfermedad, con valores de 0.549 y 0.029 d-1 para C. gloeosporioidesy R. stolonifer, respectivamente. Otros tratamientos (B2T62, B1T34, B1T34, B1T94) presentaron actividad antifúngica (valores promedio de incidencia de 35% durante todo el almacenamiento) para R. stolonifer. Los resultados de este trabajo demuestran que el efecto sinérgico del uso de biorecubrimientos de quitosán con aceites esenciales y energía UV-C controla el desarrollo de hongos causantes de antracnosis y pudrición blanda en frutos de papaya Maradol.

Jatropha curcas L. is a bioenergy crop of interest because of the high oil content in its seeds suitable for conversion into biofuels. However, its oil content is extremely variable among accessions and the mechanism of oil accumulation is poorly understood in this oleaginous species. In this study we analyzed cloned plants of three chemotypes of J. curcas collected in Chiapas, Mexico: CAC-3, COM-1 and MAP-2. All are monoecious and accumulating different amounts of seed oil: 10 %, 30 % and 54 %. We studied the expression of the β-ketoacyl-acyl carrier protein (ACP) synthase genes (KAS) in developing seeds and their relationship with the content and composition of the oil. Differences of the levels of expression of the KASI and KASII genes were found, while KASIII gene was expressed at high levels in all three chemotypes. The expression of KASI and KASII was statistically associated to the oil accumulation. Results of this study are discussed based on the regulation of the transcription of the KAS genes, in order to contribute to the understanding of the oil accumulation in the seed and could be of value for designing biotechnological strategies with which to improve this species.