Cassava, Manihot esculenta Crantz, is one of the most important crops world-wide representing the staple security for more than one billion of people. The development of dense genetic and physical maps, as the basis for implementing genetic and molecular approaches to accelerate the rate of genetic gains in breeding program represents a significant challenge. A reference genome sequence for cassava has been made recently available and community efforts are underway for improving its quality. Cassava is threatened by several pathogens, but the mechanisms of defense are far from being understood. Besides, there has been a lack of information about the number of genes related to immunity as well as their distribution and genomic organization in the cassava genome. A high dense genetic map of cassava containing 2,141 SNPs has been constructed. Eighteen linkage groups were resolved with an overall size of 2,571 cM and an average distance of 1.26 cM between markers. More than half of mapped SNPs (57.4%) are located in coding sequences. Physical mapping of scaffolds of cassava whole genome sequence draft using the mapped markers as anchors resulted in the orientation of 687 scaffolds covering 45.6% of the genome. One hundred eighty nine new scaffolds are anchored to the genetic cassava map leading to an extension of the present cassava physical map with 30.7 Mb. Comparative analysis using anchor markers showed strong co-linearity to previously reported cassava genetic and physical maps. In silico based searching for conserved domains allowed the annotation of a repertory of 1,061 cassava genes coding for immunity-related proteins (IRPs). Based on physical map of the corresponding sequencing scaffolds, unambiguous genetic localization was possible for 569 IRPs. This is the first study reported so far of an integrated high density genetic map using SNPs with integrated genetic and physical localization of newly annotated immunity related genes in cassava. These data build a solid basis for future studies to map and associate markers with single loci or quantitative trait loci for agronomical important traits. The enrichment of the physical map with novel scaffolds is in line with the efforts of the cassava genome sequencing consortium.

Potatoes are an important staple food worldwide and are the third main source of antioxidants in the human diet. One of the most important antioxidant compounds in potatoes is the anthocyanin pigments. Some reports indicate a high positive correlation between color intensity, anthocyanins content, and antioxidant level in potato tubers. The variation in anthocyanins composition and content in potato tubers among diverse germplasm sources has important nutritional and health implications and constitutes an interesting trait for potato breeding programs focused on enhancing the anthocyanin and antioxidant contents of potato materials. We identified and quantified five anthocyanidins (delphinidin, cyanidin, petunidin, pelargonidin, and peonidin) on tubers from the Colombian germplasm collection of Solanum tuberosum L. Group Phureja. The phenotypic data were merged into a genome-wide association study in order to identify genomic regions associated with the nutritional compounds’ variation in potatoes. The association was conducted using a 7520 single nucleotide polymorphisms markers matrix. Seven quantitative trait loci were identified. Chromosomes I and X harbored the most stable quantitative trait loci (QTL). Three quantitative trait loci were identified close to previously reported genes involved in the regulation of anthocyanins in potato tubers. The genomic regions of these QTL reveal presumptive candidate genes as genetic factors that are the basis for a better understanding of the genetic architecture of the regulation of nutritional compounds in potatoes.

Agraz (Vaccinium meridionale Swartz) is a shrub native to the Neotropical region of South America, including Colombia, Ecuador, Venezuela, and Peru. Known for its edible fruits valued for their nutritional, nutraceutical, and medicinal properties, the species remains underexplored despite its potential. This research aimed to investigate the genetic diversity and population structure of agraz in Colombia, focusing on native individuals from Santander and commercial individuals from Boyacá and Cundinamarca, providing insights that can support conservation and genetic improvement efforts. Methods: In this study, genotyping by sequencing (GBS) was used to analyze genetic variation and population structure in V. meridionale. The sequencing data were aligned to the V. corymbosum cv. Draper v1.0 reference genome. The obtained single-nucleotide polymorphisms (SNPs) were employed to evaluate genetic diversity, population differentiation, and inbreeding coefficients, with measures such as expected heterozygosity and F-statistics providing insights into population structure and genetic composition across regions. Results: A total of 12,910 SNPs were obtained, and the results revealed moderate genetic diversity within the agraz populations, characterized by an expected heterozygosity (He) of 0.3586. A negative Fis value indicated an excess of heterozygosity and low genetic differentiation among the sampled regions. Population structure analysis identified three distinct subpopulations, with Subpopulation 3 exhibiting the most unique genetic composition. Conclusions: This study provides the first genetic diversity analysis of V. meridionale in Colombia using the GBS approach. The findings contribute to the understanding of the species’ genetic variability and offer valuable information for conservation strategies, genetic improvement and breeding programs to enhance its agricultural potential and ensure the sustainable utilization of agraz resources.

Potato, Solanum tuberosum , is one of the highest consumed food in the world, being the basis of the diet of millions of people. The main limiting and destructive disease of potato is late blight, caused by Phytophtora infestans . Here, we present a multi-environmental analysis of the response to P. infestans using an association panel of 150 accessions of S. tuberosum Group Phureja, evaluated in two localities in Colombia. Disease resistance data were merged with a genotyping matrix of 83,862 SNPs obtained by 2b-restriction site–associated DNA and Genotyping by sequencing approaches into a Genome-wide association study. We are reporting 16 organ-specific QTL conferring resistance to late blight. These QTL explain from 13.7% to 50.9% of the phenotypic variance. Six and ten QTL were detected for resistance response in leaves and stem, respectively. In silico analysis revealed 15 candidate genes for resistance to late blight. Four of them have no functional genome annotation, while eleven candidate genes code for diverse proteins, including one leucine-rich repeat kinase.

The carnation is one of the most important products for export in the floriculture industry of Colombia. Fusariosis (a disease resulting from presence of Fusarium) appears on the crops in two forms: vascular wilt and basal rot. The first is caused by Fusarium oxysporum f. sp. dianthi, which is a well-characterized disease. The second, caused by Fusarium verticillioides (previously Fusarium roseum), is a non-characterized disease and its development in the plant has not been described in detail. The symptoms of basal rot were differentiated from vascular wilt, through infection of plants in the greenhouse, with isolates of F. verticillioides and F. oxysporum obtained from lesions of symptomatic plants. The fungi morphological characterization allowed differentiation of the isolates of these two species and their growth habits on different media. The sequencing of 8 different genes with more than 13 amplicons in the 2 species showed genetic differences that grouped the isolates into different taxa. Multilocus sequence typing analysis using DNA sequences of 8 different genetic regions confirmed the presence of F. verticillioides. In this study, the role of F. verticillioides was demonstrated in the stems of carnation in commercial crops that presented pathogenic lesions. According to the results of the study, F. verticillioides is the etiological agent that produces the basal rotting in carnation plants, alone or in association with F. oxysporum.

La yuca (Manihot esculenta Crantz) es un cultivo importante en regiones del trópico que proporciona alimento para cerca de 1000 millones de personas en todo el mundo. La enfermedad bacteriana más importante es la bacteriosis vascular causada por Xanthomonas axonopodis pv. manihotis (Xam). Recientemente se logró identificar un gen de resistencia denominado RXAM1, el cual codifica para una proteína que posee un dominio LRR (Leucine-Rich Repeat) extracelular y un dominio STK (Serine Threonine Kinase) citoplasmático. RXAM1 colocaliza con un QTL que explica el 13 % de la resistencia a la cepa CIO136 de Xam. En este trabajo se evaluó la respuesta a la infección con la cepa XamCIO136 en diez diferentes variedades de yuca lo cual permitió identificar que las variedades TMS60444, SG10735, MCOL1522, MCOL1505 y MCOL2215 fueron susceptibles, mientras que CM6438-14, CM523-7 y MBRA902 se comportaron como resistentes. Así mismo se identificaron polimorfismos tipo SNPs (Single Nucleotide Polymorphism) en el gen RXAM1 en el mismo grupo de variedades. Las variedades SG10735, CM6438-14, TMS6044 y MBRA685 presentaron el mayor nivel de polimorfismos, mientras que las variedades CM523-7, CM2177-2 y MCOL1522 fueron menos polimórficas para este gen. Los análisis estadísticos no permitieron identificar una asociación significativa entre el fenotipo y los polimorfismos identificados. Este estudio representa un primer esfuerzo con miras a asociar variantes alélicas con el fenotipo de respuesta a la bacteriosis vascular.