Genetic differentiation of native South American walnuts: a multi-marker approach to guide conservation and breeding
South American walnuts, including Juglans australis and J. boliviana, are valuable yet understudied native genetic resources. This study aimed to characterize the genetic diversity and population structure of 98 Juglans accessions from Bolivia and Argentina using a multi-tiered marker approach that combined DNA barcoding (ITS and matK regions) with high-resolution melting (HRM) pre-screening and 17 polymorphic microsatellite markers. Microsatellite markers were highly informative (mean PIC = 0.70), revealing substantial genetic diversity, with an average of 10.94 alleles per locus and a mean expected heterozygosity (He ) of 0.74. HRM analysis enabled rapid selection of the most informative barcode regions, while sequencing confirmed the phylogenetic placement of accessions within section Rhysocaryon. Population structure analysis based on microsatellite data provided the highest resolution, identifying three distinct genetic clusters (K = 3): the northern J. boliviana lineage (Cluster A), the southern J. australis lineage (Cluster B), and an introduced lineage (Cluster C). These results provide the first robust molecular evidence for genetic differentiation between native J. australis and J. boliviana. They also reveal significant introgression of exotic germplasm, confirmed by a high private allelic richness (PAr = 1.88) in the hybrid group. Overall, this study highlights the Andean region as a significant reservoir of Juglans diversity and establishes a validated genetic framework for distinguishing native South American species. These findings are essential for designing conservation strategies, defining management units, and guiding breeding programs, particularly by identifying distinct genetic lineages with potential use for timber production or as rootstocks for J. regia, likely due to their adaptation to local and subtropical soil conditions.
Towards a sustainable fruit production: deciphering the effect of rootstock x scion interaction on the adaptability of stone fruit trees (Prunus spp.) to climate change”
El objetivo general es estudiar los efectos de nuevos portainjertos híbridos de Prunus creados por CEAF sobre los mecanismos moleculares, fisiológicos y reproductivos que actúan a nivel de raíces, brotes y la interacción entre portainjerto y variedad en árboles frutales de carozo sometidos a déficit hídrico y estrés por calor.