Abstract
Significant differences in softening rate have been reported between melting flesh in peach and nectarine varieties. This trait seems to be controlled by several genes. We aimed to identify candidate genes involved in fruit softening rate by integrating quantitative trait loci (QTL) and expression QTL (eQTL) analyses, comparing siblings with contrasting softening rates. We used a segregating population derived from nectarine cv. ‘Venus’ selfing, which was phenotyped for softening rate during three seasons. Six siblings with high (HSR) and six with low softening rate (LSR) were sequenced using RNA-Seq. A group of 5,041 differentially expressed genes was identified. Also, we found a QTL with a LOD (logarithm of odds) score of 9.7 on LG4 in all analyzed seasons. Furthermore, we detected 1,062 eQTLs, of which 133 were found co-localizing with the identified QTL. Gene Ontology (GO) analysis showed ‘Response to auxin’ as one the main over-represented categories. Our findings suggest over-expression of auxin biosynthetic related genes in the HSR group, which implies a higher expression and/or accumulation of auxin, thereby triggering fast softening. Conversely, the LSR phenotype might be explained by an altered auxin-homeostasis associated with low auxin levels. This work will contribute to unraveling the genetic mechanisms responsible for the softening rate in peaches and nectarines and lead to the development of molecular markers.
Highlights
Peach [Prunus persica (L.) Batsch] is the second most predominant temperate tree fruit species in worldwide production
We have developed an integrative analysis involving conventional quantitative trait loci (QTL), expression QTL (eQTL), and transcriptome profiling analysis focused on siblings with contrasting phenotypes for flesh softening in peach fruit
A conventional QTL was identified at linkage group 4 (LG4) co-localizing with a previously reported QTL associated with fruit firmness and the slow melting flesh character (Serra et al, 2017)
Summary
Peach [Prunus persica (L.) Batsch] is the second most predominant temperate tree fruit species in worldwide production. Peach belongs to the Rosaceae family (Bassi and Monet 2008; Shulaev et al, 2008), and has become the most economically important crop in Prunus (Abbott et al, 2002), a genus that includes nectarine, plum, apricot, cherry, and almond (Arús et al, 2012). Peach is one of the best genetically characterized species in the Rosaceae family (Ogundiwin et al, 2009) and it has been used as a model for genetics and genomics studies of tree fruit species Peach has a small genome (ca. 224.6 Mb) (Verde et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
