Cacao (Theobroma cacao L.), the source of chocolate, is one of the most important commodity products worldwide that helps improve the economic livelihood of farmers. Diseases like frosty pod rot caused by Moniliophthora roreri and witches’ broom caused by Moniliophthora perniciosa limit the cacao productivity, this can be solved by using resistant varieties. In the current study, we sequenced 229 cacao accessions using genotyping-by-sequencing to examine the genetic diversity and population structure employing 9,003 and 8,131 single nucleotide polymorphisms recovered by mapping against two cacao genomes (Criollo B97-61/B2 v2 and Matina 1-6 v1.1). In the phenotypic evaluation, three promising accessions for productivity and 10 with good tolerance to the frosty pod rot and witches’ broom diseases were found. A genome-wide association study was performed on 102 accessions, discovering two genes associated with productivity and seven to disease resistance. The results enriched the knowledge of the genetic regions associated with important cacao traits that can have significant implications for conservation and breeding strategies like marker-assisted selection.

Seventy-four volatile compounds were identified and quantified from cocoa liquors of the ICS 95 and TCS 01 varieties produced in the department of Santander, Colombia. The compounds were extracted using the solid phase microextraction with head space (SPME-HS) technique, and identified by gas chromatography coupled to mass spectrometer (GC-MS) by comparing the mass spectra of each compound in the Wiley 275L library of mass spectra and the Kovats retention index (IK) ratio. A semi-quantitative method was proposed that included toluene as an internal standard to normalize the degree of recovery between samples and a response factor for each family, calculated using a compound characteristic of that functional group. The results associated with response factors for each family or group of compounds such as alcohols, acids, aldehydes, ketones, esters and pyrazines (2.19, 1.02, 2.84, 0.38, 6.38, 0.88 respectively) were different between families, however, there was no difference between compounds within the same family. The implemented method obtained a DOD and DML of 0.024 µg/kg and 0.037 µg/kg respectively and an accuracy expressed as percentage recovery (of characteristic compounds per family) of 96% on average. According to the precision of the method, the results show that the concentrations have an average coefficient of variation (%CV) of 7.38% assuring repeatability and good precision. Finally, for the analyzed and quantified samples, it was found that the compounds with higher concentration were acetic acid (42.633 mg/kg), 2-phenylethyl acetate (29.44 mg/kg), 2.3-butanediol (345.39 mg/kg), 2-phenylethanol (12.595mg/kg) and 2.3.5.6-tetramethylpyrazine (8.601 mg/kg).

Genome wide association study reveals novel candidate genes associated 1 with productivity and disease resistance to Moniliophthora spp. in cacao 2 (Theobroma cacao L.) 3 4 5

Una correcta cosecha Cacao implica determinar si la mazorca se encuentra en un adecuado estado de madurez. No obstante, este proceso suele darse de manera artesanal y basarse en atributos como el tamaño y color de la mazorca, características que difieren según la variedad cultivada, lo cual dificulta su estandarización. Con el fin de simplificar la cantidad de variables y presentar un método automatizado, el presente trabajo propone desarrollar una herramienta portable, de bajo costo, y hecha a medida, la cual hace uso de una red neuronal convolucional para indicar si una mazorca de cacao se encuentra en el momento oportuno para ser cosechada. Entre los principales resultados del presente trabajo se encuentran: 1) la construcción de tres conjuntos de datos etiquetados (1992 imágenes cada uno), y 2) un sistema embebido con una precisión de 34.83% mAP (mean Average Precision). Finalmente, se demuestra estadísticamente que el tamaño de las imágenes (4033x4033 p, 1009x1009 p y 505x505 p) no incide sobre la eficacia del entrenamiento.