Nicaragua is located in the Mesoamerican diversity centre for common beans (Phaseolus vulgarisL.). Yet, there is insufficient knowledge of the molecular characteristics of most common bean landraces in Nicaragua. The objectives of the present study were to investigate the genetic diversity of common bean landraces and to identify promising sources of genetic variation for breeding purposes. Two cultivars and 40 landraces never studied before were selected from a collection based on the geographic origin, seed coloration and information provided by farmers. Fourteen microsatellite markers distributed in different linkage groups were analysed. The study revealed that there is a high genetic diversity (mean 8.9 alleles per locus). The populations showed structuring into three groups where seed weight had a strong relationship with population clustering. At least 20% of the populations hold promising allelic variation and potential for good market acceptance that could be maximized in breeding programmes. Additionally, four markers revealed a high correlation with seed length, width and weight, suggesting that marker-assisted selection for these yield-determinant traits could be straightforward. Nonetheless, more marker–trait associations should be addressed in order to enforce this practice.

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Germplasm improvement is a conceivable solution for increasing food production in developing countries. The objectives of the present study were to incorporate the genetic diversity of two Nicaraguan common bean landraces into a segregating population and to evaluate its potential as breeding material. Adapted landraces PV0006 and PV0023 were selected as parents for single crosses based on molecular and phenotypic characteristics. The results indicate that we succeeded in reshuffling most of the genetic diversity of both parents into a segregating population. The level of allele recombinations suggests that theoretically between 128 and 1024 different pure lines could be obtained. We found putative associations between alleles and yield‐determinant components. Computer simulations demonstrated that the pedigree method and the marker selection of the most segregating individuals in the F1 generation could improve the genetic gains for yield. These findings expose the potential of this segregating population and the feasibility of local landraces for bean improvement.

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Introduction. Genetic diversity, registration, and traceability of cacao planting material are the essential tripod to support its sustainable cultivation. In Nicaragua, cocoa planting material is mostly obtained from seeds, which leads to great variability in yield, bean quality, and tolerance to pests and diseases. Farmers, technical staff, development projects, and investors depend on a limited supply of elite trees as a reliable source of genetic material to support new cacao fronts and meet market quality standards. Therefore, the development of a national genetic improvement program and a planting material traceability system in Nicaragua are necessary to improve the sustainability of cacao cultivation. Objective. To evaluate the genetic resources on farms and provide information for future breeding programs, as well as to lay foundation for a national traceability and certification system. Materials and methods. Fourty-nine elite trees selected by farmers in the main producing regions in Nicaragua between 2018 and 2020 were sampled. Ninety-three SNP markers were used to characterize them and resolve their genetic origins. Results. The evaluated cacao trees had a narrow genetic background, mainly composed of hybrids with Amelonado (36 %), Criollo (17 %) and Iquitos (15 %) origins. A set of trees with high genetic diversity that could be incorporated into a selection and breeding program was identified. Conclusion. Fingerprinting with SNP markers was a useful tool for evaluating the genetic links of cultivated cacao and can be used for varietal identity test at the farm level. The study provided the basis for developing both a breeding program and a traceability system of cacao planting material in Nicaragua.