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- Author or Editor: Maria Jose Gonzalo x
Melon (Cucumis melo) is one of the principal vegetable crops for fresh market, for which a large number of breeding programs, oriented to generate inbred pure lines and hybrids, is established worldwide. The process to obtain and select these lines has been highly accelerated by the use of biotechnological techniques such as the generation of doubled haploid line (DHL) populations and molecular markers. Moreover, the use of DHLs in genetic studies is a useful tool because of their complete homozygosity and the permanent availability of plant material perpetuated by seed. In this work, the parthenogenetic response of 17 melon genotypes and the F1 hybrid PI 161375 × Spanish cultivar Piel de Sapo (PS) was studied considering three stages along the in vitro DHL generation process. The response of the analyzed melon cultivars was heterogeneous through the DHL generation with different limiting steps for each genotype. The response of the PI 161375 × PS hybrid was more similar to the male (PS) than the female parent (PI 161375), although the response of the maternal genotype was higher for some stages. This points to the important role of alleles from both parents in the different steps of the DHL generation process, and it could explain the identification of six genomic regions with distorted allelic segregation skewed toward PS or PI 161375. This hybrid was used to generate a population of 109 DHLs, the gametophytic origin of which was confirmed by flow cytometry and molecular markers.
Reliable analysis of plant traits depends on the accuracy of scoring the phenotype. We report here on the efficacy of two methods in the detection of quantitative trait loci (QTL) controlling fruit morphology in three segregating tomato (Solanum spp.) F2 populations using the software program, Tomato Analyzer. The first method uses fruit morphology attributes such as fruit shape index, blockiness, pear shape, indentation area, and angles of the fruit along the boundary. The second method uses morphometric points to quantify shape. The morphometric data were subjected to principle components analysis (PCA). QTL that control the fruit morphology attributes and the morphometric PCA were identified that revealed that the methods were comparable in that they resulted in nearly identical loci. Novel attributes were added to Tomato Analyzer that improved versatility of the program in measuring additional morphological features of fruit. We demonstrated that these novel attributes permitted identification of QTL controlling the traits.