Tomato genomic prediction for good performance under high-temperature and identification of loci involved in thermotolerance response

Many studies showed that few degrees above tomato optimum growth temperature threshold can lead to serious loss in production.Therefore,the development of innovative strategies to obtain tomato cultivars with improved yield under high temperature conditions is a main goal both for basic genetic studies and breeding activities.In this paper,a F4 segregating population was phenotypically evaluated for quantitative and qualitative traits under heat stress conditions.Moreover,a genotyping by sequencing(GBS)approach has been employed for building up genomic selection(GS)models both for yield and soluble solid content(SCC).Several parameters,including training population size,composition and marker quality were tested to predict genotype performance under heat stress conditions.A good prediction accuracy for the two analyzed traits(0.729 for yield production and 0.715 for SCC)was obtained.The predicted models improved the genetic gain of selection in the next breeding cycles,suggesting that GS approach is a promising strategy to accelerate breeding for heat tolerance in tomato.Finally,the annotation of SNPs located in gene body regions combined with QTL analysis allowed the identification of five candidates putatively involved in high temperatures response,and the building up of a GS model based on calibrated panel of SNP markers.

Genetic Diversity within Wild Potato Species (Solanum spp.) Revealed by AFLP and SCAR Markers

Exploitation of variability displayed by wild Solanum species for breeding the cultivated potato (S. tuberosum) requires phenotypic and genotypic characterization of germplasm resources. In the present work, a collection of 15 wild Solanum species was investigated for resistance to pathotype Ro2 of the nematode Globodera rostochiensis. Most of the genotypes reduced reproduction of the nematode, compared to the control variety Spunta, a highly resistant genotype being an accession of S. tuberosum spp. andigena. The genetic variability of the Gro1 gene cluster, which confers resistance to some pathotypes of G. rostochiensis, was then studied in the Solanum species used in this study. For this purpose, SCAR markers for eight paralogues of Gro1 gene were developed. No species showed the same pattern of the resistant control genotype. Moreover, wide-genome variability was also assessed by using AFLP markers, which allowed species-specific markers to be identified for each genotype analyzed.