The peach [Prunus persica L. (Batsch)] slow ripening (SR) trait is a mutation preventing the normal ripening process. Individuals with this phenotype are discarded in peach breeding programs. This trait is determined by a single gene (Sr/sr), where the recessive homozygote (sr/sr) confers the SR phenotype, and has been mapped to linkage group 4 of the peach genome. A large deletion of 26.6 kb containing the sequence of a NAC transcription factor has been proposed as the causal mutation. Two dominant markers based on the sequence of this region have been assayed previously and found to be diagnostic (genotypes always predicted the phenotypes). However, their dominant nature-a null allele for the marker was associated with the sr allele-made it impossible to predict the individuals that carried the SR trait. Here we used resequencing information to develop a codominant molecular marker for the SR trait in peach. The marker was validated in the 'Belbinette' 9 'Nectalady' F1 and the 'Venus' F2 populations, and in 27 lines, 18 of which are known to carry the sr allele. The marker cosegregated with the SR phenotype in all cases, allowing the discrimination of two DNA fragments of different size associated with normal-ripening alleles, in addition to a third fragment associated with the sr allele. The utility of this marker in peach breeding programs is discussed.Spanish Ministry of Economy and Knowledge AGL2012-40228-C02-01 Fondo de Areas Prioritarias Centro de Regulacion del Genoma 15090007 CORFO Consorcio Biofrutales 13 CTI-21520-SP03 13 CTI-21520-SP04 FONDECYT 1160584 FONDEF Genoma G13i10005 CORFO-Innova 09PMG724

Fruit development is a complex process that involves the interplay of cell division, expansion, and differentiation. As a model to study fruit development, nectarines incapable of ripening were described as slow ripening. Slow ripening fruits remained firm and exhibited no rise in CO2 or ethylene production rates for one month or more at 20 °C. Different studies suggest that this trait is controlled by a single gene (NAC072). Transcriptome analysis between normal and slow ripening fruits showed a total of 157, 269, 976, and 5.224 differentially expressed genes in each fruit developmental stage analyzed (T1, T2, T3, and T7, respectively), and no expression of NAC072 was found in the slow ripening individuals. Using this transcriptomic information, we identified a correlation of NAC072 with auxin-related genes and two genes associated with terpene biosynthesis. On the other hand, significant differences were observed in hormonal biosynthetic pathways during fruit development between the normal and slow ripening individuals (gibberellin, ethylene, jasmonic acid and abscisic acid). These results suggest that the absence of NAC072 by the direct or indirect expression control of auxins or terpene-related genes prevents normal peach fruit development.