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14 Pags.- 6 Figs.- 3 Tabls. Copyright © 2021 Amri, Font i Forcada, Giménez, Pina and Moreno. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). ; Grafting is an ancient plant propagation technique widely used in horticultural crops, particularly in fruit trees. However, the involvement of two different species in grafting may lead to lack of affinity and severe disorders between the graft components, known as graft-incompatibility. This complex agronomic trait is traditionally classified into two categories: "localized" (weak graft unions with breaks in cambial and vascular continuity at the graft interface and absence of visual symptoms in scion leaves and shoots) and "translocated" (degeneration of the sieve tubes and phloem companion cells at the graft interface causing translocation problems in neighboring tissues, and reddening/yellowing of scion leaves). Over the decades, more attention has been given to the different mechanisms underlying the "localized" type of graft-incompatibility; whereas the phenylpropanoid-derived compounds and the differential gene expression associated with the "translocated" graft-incompatibility remain unstudied. Therefore, the aim of this study was to shed light on the biochemical and molecular mechanisms involved in the typical "translocated" graft-incompatibility of peach/plum graft-combinations. In this study, the "Summergrand" (SG) nectarine cultivar was budded on two plum rootstocks: "Adara" and "Damas GF 1869". "Translocated" symptoms of incompatibility were shown and biochemically characterized in the case of "SG/Damas GF 1869" graft-combination, 3 years after grafting. Non-structural carbohydrates (soluble sugars and starch), phenolic compounds and antioxidant activity, were significantly enhanced in the incompatible graft-combination scion. Similarly, the enzymatic activities of the antioxidant enzyme peroxidase, the phenylalanine ammonia-lyase (PAL) and polyphenol oxidase involved in the phenylpropanoid pathway were significantly affected by the incompatible rootstock "Damas GF 1869", inducing higher activities in the scion than those induced by the compatible rootstock "Adara". In addition, a positive and strong correlation was obtained between total phenol content, antioxidant capacity and the expression of the key genes involved in the phenylpropanoid pathway, PAL1 and PAL2. Regarding the "SG/Adara" graft-combination, there were neither external symptoms of "translocated" incompatibility nor significant differences in the biochemical and molecular parameters between scion and rootstock, proving it to be a compatible combination. The differential expression of PAL genes together with the biochemical factors cited above could be good markers for the "translocated" peach/plum graft-incompatibility. ; This research was funded by the Spanish Ministry of Science, Innovation and Universities (MICINN) grants RFP2015-00019 and RTI2018-094176-R-C33, co-funded by FEDER and the Regional Government of Aragon (A44 and T07-17R). RA received a Master's fellowship awarded by the CIHEAM-IAMZ. ; Peer reviewed

18 Pags.- 6 Figs.- 1 Tabl. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. ; Apple is widely cultivated in temperate regions. The beneficial properties of apple for preventing several illnesses are widely known. Nevertheless, qualitative variables such as sweetness or sourness may influence consumer satisfaction; they are critical factors for fruit consumption and essential in plant breeding. In the present work, 155 apple accessions were assessed during five consecutive years (2014–2018). Four individual sugars and seven organic acids were analysed by HPLC. A mixed-effects model was fitted with accessions and the years' climatic features as independent variables. A cluster analysis was applied on the mixed-effects model coefficients. Four groups were considered as optimum. Genetics seemed to have the strongest effect and showed clear differences between accession groups, while climate effects were strong only for certain compounds and had a more horizontal behaviour equally affecting the different accession groups. In fact, non-Spanish cultivars tended to concentrate, while autochthone accessions had a much wider spread. Individual sugars and acids concentrations correlated negatively with precipitation and positively with temperature range and solar radiation in all accession groups. The geographic region where the orchard is grown is thus very important in the resulting metabolites profiles. Moreover, apple genetics would also play a decisive role as highlighted in the cluster analysis. ; This work was funded by the Spanish Ministry of Science Innovation and Universities grants RFP 2012-00020, RFP 2015-00019 and PIE201640E070, cofounded by FEDER, and the Regional Government of Aragon (A44, T07_17R, A22_20R, and P. Mignard grant). ; Peer reviewed

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