The potato (Solanum tuberosum L.) is the fourth most important crop food in the world and Colombia has one of the most important collections of potato germplasm in the world (the Colombian Central Collection-CCC). Little is known about its potential as a source of genetic diversity for molecular breeding programs. In this study, we analyzed 809 Andigenum group accessions from the CCC using 5968 SNPs to determine: 1) the genetic diversity and population structure of the Andigenum germplasm and 2) the usefulness of this collection to map qualitative traits across the potato genome. The genetic structure analysis based on principal components, cluster analyses, and Bayesian inference revealed that the CCC can be subdivided into two main groups associated with their ploidy level: Phureja (diploid) and Andigena (tetraploid). The Andigena population was more genetically diverse but less genetically substructured than the Phureja population (three vs. five subpopulations, respectively). The association mapping analysis of qualitative morphological data using 4666 SNPs showed 23 markers significantly associated with nine morphological traits. The present study showed that the CCC is a highly diverse germplasm collection genetically and phenotypically, useful to implement association mapping in order to identify genes related to traits of interest and to assist future potato genetic breeding programs.

GENÉTICA VEGETAL Y BIODIVERSIDAD RESUMENEl marchitamiento vascular ocasionado por el hongo Fusarium oxysporum se considera el principal limitante en la producción de uchuva (Physalis peruviana) en Colombia. Se han identificado genotipos de P. peruviana y la especie relacionada P. floridana con diferentes niveles de reacción a F. oxysporum. En el presente estudio, se evaluaron los genotipos con el fin de complementar el conocimiento de la diversidad citogenética en Physalis y el diseño de estrategias de hibridación como apoyo al mejoramiento del cultivo de la uchuva. Se determinó el número de cromosomas en células en división mitótica de ápices radicales de plantas cultivadas in vitro, para lo cual se estimó como hora mitótica promedio las 12:00 para P. peruviana, y las 10:00 para P. floridana. Se encontraron dotaciones cromosómicas de 2n = 4x = 48 y 2n = 2x = 24 para cada una de las dos especies. Adicionalmente, se realizó un análisis por citometría de flujo, en el cual se detectó variación en el contenido de ADN nuclear en P. peruviana con 2,33 pg para el genotipo 2n = 24 y entre 5,77 y 8,12 pg para los genotipos 2n = 48. En P. floridana el contenido de ADN fue 2,29 pg para el genotipo con número cromosómico 2n = 24 y 4,03 pg para el genotipo 2n = 48. Se encontró un efecto significativo (α = 0,01) del número de cromosomas sobre el contenido de ADN nuclear para las dos especies.Palabras claves: cariotipo, citometría de flujo, conteo cromosómico. ABSTRACTVascular wilt caused by the fungus Fusarium oxysporum is considered the main constraint of cape gooseberry, Physalis peruviana, production in Colombia. P. peruviana and P. floridana genotypes with differential resistance responses against F. oxysporum have been identified previously. In the present study, the genotypes were evaluated in order to complement the knowledge of cytogenetics diversity in Physalis and to design hybridization strategies to support breeding of cape gooseberry crop. The chromosome number in mitotic dividing cells from root-tips of tissue culture plantlets was determined, from which the average mitotic hour was estimated at 12:00 hours for P. peruviana and 10:00 for P. floridana. Chromosomic complements of 2n = 4x = 48 and 2n = 2x = 24 were found for each one of the two species. Additionally, flow cytometry analyses detected variation within P. peruviana with a nuclear DNA content of 2.33 pg for the 2n = 24 genotype and variations ranged from 5.77 to 8.12 pg for 2n = 48 genotypes. In P. floridana DNA content was 2.29 pg in the 2n = 24 genotype and 4.03 pg in the 2n = 48 genotype. There was a significant effect (α = 0.01) of the number of chromosomes on nuclear DNA content for the two species.

The cape gooseberry (Physalis peruviana L.) is one of the most important Colombian exotic fruits. Chromosome doubling of anther-derived plants is a key factor in the application of double haploid technology for the genetic improvement of crops. In the present study, axillary buds from four haploid cape gooseberry genotypes were used to evaluate artificial chromosome doubling induced by colchicine and its effects on ploidy level and pollen fertility. Three concentrations of colchicine (5, 10 and 15 mM) and three exposure times (2, 4 and 6 h) were used to determine the best treatment for the generation of fertileB plants from axillary buds of haploid genotypes. The colchicine increased both the number of chromosomes, from 36 to 129, and the average chloroplasts in stomata guard cell, from 4.5 to 23.8. The optimal chromosome doubling of the haploids was obtained with the 5 mM colchicine solution and 2 h exposure time. This protocol produced chromosome doubling in over 60% of the regenerants of the four haploid genotypes, with a high level of fertility. Morphologically, the fertile mixoploid plants showed variation in the vegetative, flowering and fruit characteristics, as compared to the haploid plants.

Slow‐darkening pinto common bean (Phaseolus vulgaris L.) cultivar ‘Wildcat’ (Reg. no. CV‐345, PI 698190) was released by the University of Nebraska dry bean breeding program in 2018. It was bred for adaptation to western Nebraska growing conditions and enhanced resistance to bean rust, common bacterial blight (CBB), and Bean common mosaic virus (BCMV). The yield of Wildcat was comparable to conventional and slow‐darkening pinto bean cultivars grown in Nebraska from 2015 to 2020. During the 2017 Western Regional Bean Trial, 2017 Midwest Regional Performance Nursery, and 2018 Cooperative Dry Bean Nursery, Wildcat had a higher seed yield than ‘Twin Falls’, ‘Nez Perce’, ‘Black Foot’, ‘Montrose’, ‘Buster’, ‘ND‐Palomino’, and ‘La Paz’ at some locations. Wildcat has the Ur‐11 gene that confers resistance to all but one known bean rust race and carries the Indel NDSU_IND_11_48.459.896 marker tagging the Ur‐11 locus. Wildcat also has the SAP6 sequence characterized amplified region (SCAR) marker linked to a major CBB resistance quantitative trait locus, with an intermediate CBB rating (5.0) under field conditions at western Nebraska in 2020. Wildcat also carries the single dominant I gene that confers resistance to all non‐necrotic strains of BCMV and the SW13 SCAR marker linked to the I gene for resistance to BCMV. Wildcat has white flowers, blooms 46 d after planting, and is a full‐season bean, maturing 93 d after planting. The seed size of Wildcat, 43.3 g 100 seeds–1 on average, was significantly larger than current conventional and slow‐darkening pinto beans.

The cape gooseberry, Physalis peruviana L., is a crop that is transitioning from a semi-wild rural food source to becoming an international export commodity fruit deserving of greater attention from the scientific community, producers, policy makers and opinion makers. Despite its importance, the crop has serious technological development challenges, mainly associated with the limited supply of genetically improved materials for producers and consumers. In the present study, the level of ploidy of 100 genotypes of gooseberry from a working collection was determined by counting the number of chromosomes and chloroplasts, to include them in the breeding program. The number of chromosomes in dividing cells of root-tip meristems, as well as the number of chloroplasts per guard cell, from plants grown in vitro and ex vitro conditions were determined. Haploid with 24 chromosomes, doubled haploid-tetraploid with 48 chromosomes, aneuploid (44 and 49 chromosomes) and mixoploid genotypes with 36 to 86 chromosomes were found. The number of chloroplasts / cell guard ranged from 4-8, 6-16, 7-16 and 9-21 for the haploid, aneuploid, doubled haploid-tetraploid and mixoploid genotypes, respectively. Evidence of a high cytogenetic diversity in the evaluated genotypes.