Suchergebnisse

Background: The importance of Indian germplasm as origin and primary center of diversity of cultivated melon is widely accepted. Genetic diversity of several collections from Indian has been studied previously, although an integrated analysis of these collections in a global diversity perspective has not been possible. In this study, a sample of Indian collections together with a selection of world-wide cultivars to analyze the genetic diversity structure based on Genotype by Sequence data. Results: A set of 6158 informative Single Nucleotide Polymorphism (SNP) in 175 melon accessions was generated. Melon germplasm could be classified into six major groups, in concordance with horticultural groups. Indian group was in the center of the diversity plot, with the highest genetic diversity. No strict genetic differentiation between wild and cultivated accessions was appreciated in this group. Genomic regions likely involved in the process of diversification were also found. Interestingly, some SNPs differentiating inodorus and cantalupensis groups are linked to Quantitiative Trait Loci involved in ripening behavior (a major characteristic that differentiate those groups). Linkage disequilibrium was found to be low (17 kb), with more rapid decay in euchromatic (8 kb) than heterochromatic (30 kb) regions, demonstrating that recombination events do occur within heterochromatn, although at lower frequency than in euchromatin. Concomitantly, haplotype blocks were relatively small (59 kb). Some of those haplotype blocks were found fixed in different melon groups, being therefore candidate regions that are involved in the diversification of melon cultivars. Conclusions: The results support the hypothesis that India is the primary center of diversity of melon, Occidental and Far-East cultivars have been developed by divergent selection. Indian germplasm is genetically distinct from African germplasm, supporting independent domestication events. The current set of traditional Indian accessions may be considered as a population rather than a standard collection of fixed landraces with high intercrossing between cultivated and wild melons. ; Javier Forment from the Bioinformatics Core Service at IBMCP for support in bioinformatics analysis. We also acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). NPS Dhillon was supported by long-term strategic donors to the World Vegetable Center: Republic of China (Taiwan), UK aid from the UK government, United States Agency for International Development (USAID), Australian Centre for International Agricultural Research (ACIAR), Germany, Thailand, Philippines, Korea, and Japan.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO)-FEDER grant AGL2015–64625-C2-R to AJM (project conception, experiments, data acquisition and analysis, manuscript writing, publication costs), AGL2017–85563-C2–1-R and the PROMETEO/2017/078 grant funded by Generalitat Valenciana (Conselleria d'Educació, Investigació, Cultura i Esport) to BP (project conception, provide samples and manuscript drafting). AD was supported by a Jae-Doc contract from CSIC (experiments and manuscript drafting).

43 Pags.- 2 Tabls.- 4 Figs.- 4 Suppl. Tabls.- 1 Suppl. Fig. The definitive version is available at: http://link.springer.com/journal/11295 ; Fruit quality is an essential criterion used to select new cultivars in peach breeding programs and is determined based on a combination of organoleptic and nutritional traits. The aim of this study was to identify quantitative trait loci (QTLs) for fruit quality traits in an F1 nectarine population derived from 'Venus' and 'Big Top' cultivars. The progeny were evaluated over 4 years for agronomical and biochemical characteristics and genotyped using simple sequence repeat (SSR) markers and 'IPSC 9K peach SNP array v1'. Two genetic maps were constructed using 411 markers. The 'Venus' map spanned 259 cM on nine linkage groups (LGs) with 104 markers. The 'Big Top' map spanned 464 cM on 10 LGs with 122 markers. Single or Multiple QTL models mapping was applied separately for each year and all years combined. A total of 54 QTLs mapped over 12 LGs belonged to seven peach chromosomes. Most of the QTLs were consistent over the 4 years of study and were validated with the multi-year analysis. QTLs for total phenolic, flavonoid, and anthocyanin contents were reported for the first time in peach. LG 4 in 'Venus' and LG 5 in 'Big Top' showed the highest numbers of QTLs. This work represents the first study in an F1 nectarine family to identify peach genomic regions that control fruit quality traits using 'IPSC 9K SNP array v1' and provides useful information for marker-assisted breeding to produce peaches with better antioxidant content and healthy attributes. ; This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) grants AGL-2008-00283, AGL2011- 24576, and AGL2014-52063-R and was co-funded by the FEDER and the Regional Government of Aragón (A44) with European Social Fund. W. Abidi was supported by a JAE-Pre fellowship from the Consejo Superior de Investigaciones Científicas (CSIC), which enabled him to visit the University of California, Davis, and the IBMCP, Valencia, Spain. J.L. Zeballos received a master fellow funded by the Spanish Agency for International Cooperation and Development (AECID). ; Peer reviewed

8 Pags.- 1 Tabl. 2 Figs. From author's contribution at VIII International Peach Symposium (Matera, Italy. June 17-20, 2013). The definitive version is available at: http://www.actahort.org/index.htm ; Fruit quality is the main criterion used for selection of new varieties in peach, and it is usually defined by the conjunction of organoleptic and nutritional traits and postharvest behavior. The aim of this study was the identification of quantitative trait loci (QTL) for several fruit quality traits using an F1 segregating population of 75 seedlings derived from the cross between 'Venus' and 'Big Top' nectarine cultivars. The progeny was evaluated over several years for agronomic and pomological characteristics (including basic quality traits and antioxidant compounds content) and also genotyped using SNPs included in the 'IPSC 9K peach SNP array v1' developed by the International Peach SNP Consortium, which carries 8,144 SNPs. Two preliminary dense genetic linkage maps were constructed for 'Venus' and 'Big Top', with 160 and 208 markers placed onto 11 linkage groups, respectively. A second round was used to identify QTLs that were mapped over twelve LG representing seven peach chromosomes. Some of the QTLs mapped in the same position of previously reported QTLs, interestingly QTLs for fructose in LG6 and phenolic compounds in LG2 were detected for the first time. LG4 in 'Venus' and LG5 in 'Big Top' maps presented the highest density of QTLs controlling several traits. This work represents the first study identifying QTLs for fruit quality traits using the high-density SNP array 'IPSC 9K peach SNP array v1' in an F1 nectarine family. ; This work was supported by the Spanish MICINN (Ministry of Science and Innovation) grants AGL-2008-00283 and AGL2011-24576 and co-funded by FEDER and the Regional Government of Aragón (A44). W. Abidi and J.L. Zeballos were supported by a JAE-Pre fellowship from CSIC and a Master fellow funded for the AECID (Spanish Agency for International Cooperation and Development). ; Peer reviewed

We have studied a genomic library of introgression lines from the Solanum pimpinellifolium accession TO-937 into the genetic background of the "Moneymaker" cultivar in order to evaluate the accession's breeding potential. Overall, no deleterious phenotypes were observed, and the plants and fruits were phenotypically very similar to those of "Moneymaker," which confirms the feasibility of translating the current results into elite breeding programs. We identified chromosomal regions associated with traits that were both vegetative (plant vigor, trichome density) and fruit-related (morphology, organoleptic quality, color). A trichome-density locus was mapped on chromosome 10 that had not previously been associated with insect resistance, which indicates that the increment of trichomes by itself does not confer resistance. A large number of quantitative trait loci (QTLs) have been identified for fruit weight. Interestingly, fruit weight QTLs on chromosomes 1 and 10 showed a magnitude effect similar to that of QTLs previously defined as important in domestication and diversification. Low variability was observed for fruit-shape-related traits. We were, however, able to identify a QTL for shoulder height, although the effects were quite low, thus demonstrating the suitability of the current population for QTL detection. Regarding organoleptic traits, consistent QTLs were detected for soluble solid content (SSC). Interestingly, QTLs on chromosomes 2 and 9 increased SSC but did not affect fruit weight, making them quite promising for introduction in modern cultivars. Three ILs with introgressions on chromosomes 1, 2, and 10 increased the internal fruit color, making them candidates for increasing the color of modern cultivars. Comparing the QTL detection between this IL population and a recombinant inbred line population from the same cross, we found that QTL stability across generations depended on the trait, as it was very high for fruit weight but low for organoleptic traits. This difference in QTL stability may be due to a predominant additive gene action for QTLs involved in fruit weight, whereas epistatic and genetic background interactions are most likely important for the other traits. ; The authors want to thank the funding from grant AGL2015-65246-R (Spanish MINECO, co-financed by European Union FEDER programme), and the EU Framework Program Horizon 2020 COST Action FA1106 Quality Fruit for networking activities. WB was supported by a fellowship granted by the Universidad de Costa Rica and CSIC-Spain by way of a collaboration agreement between CSIC/UCR. GL-C was supported by a JAE-Doc contract by CSIC co-funded by the European Social Fund (ESF). ; Peer reviewed ; Peer Reviewed

This work was supported in part by the Spanish MINECO Project AGL2015-65246-R co-financed by EU FEDER, MINECO Project AGL2011-26957, and the Bilateral agreements of Scientific and Technological Cooperation between the Spanish National Research Council (CSIC) and the Italian National Research Council (CNR). Funding for this project was provided through TRADITOM. TRADITOM has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 634561. Networking activities were supported by COST action Fruit Quality FA 1106. ; Peer reviewed