Utilization of genetic resources for the introduction and adaptation of exotic vegetable crops: The case of pepino (Solanum muricatum)

Summary Pepino (Solanum muricatum), a vegetatively propagated plant from the Andean region used for its edible fruits, has been identified as a potential crop for greenhouse cultivation in Mediterranean regions. However, attempts for introducing it have been unsuccessful, either because of the low yield, poor fruit quality, or both. Screening of germplasm under Mediterranean conditions showed that sources of variation for high yield existed in the cultivated genepool and that wild species S. caripense and S. tabanoense could contribute to a considerable improvement of soluble solids content (SSC) of pepino. Progenies obtained after crossing genetically distant (AFLP-based) parental clones were heterotic for yield, and allowed the selection of clones with an improved combination of yield and SSC. As a result of this intraspecific programme, two new improved cultivars (‘Turia’ and ‘Valencia’), which outperform the rest of cultivars available, have been selected for cultivation in Mediterranean conditions. The interspecific programme involved the selection of clones with high yield and SSC in backcross generations. The results show that introgression of genes from the wild species can contribute to improve the SSC of pepino. The backcross programme is in an advanced stage and new cultivars derived from the interspecific crosses are expected to be released in a near future. New prospects for the future in pepino breeding include the genetic transformation, the establishment of a genetic map, and the use of the genomic information from related Solanaceae important crops. All the information obtained is illustrative for the breeding for adaptation of vegetatively propagated crops.     

Inheritance and relationships of important agronomic traits in almond

The inheritance of 16 important agronomic traits and its relationship were studied for four years in a population of 167 almond [P. dulcis (Mill.) D.A. Webb] seedlings obtained from a cross between the French selection ‘R1000’ (‘Tardy Nonpareil’ × ‘Tuono’) and the Spanish cultivar ‘Desmayo Largueta’. For some traits (blooming and leafing date) descendants segregated between the value of both progenitors, meanwhile for others the mean of the offspring was lower (bloom density, productivity and ripening date) or higher (in-shell/kernel ratio and double kernels). As expected, kernel bitterness and self-incompatibility behaved as monogenic traits. Some important correlations between traits were detected. The implications of the transmission and the correlation of these traits in the breeding programmes are discussed.