Thorough Characterization of ETHQB3.5, a QTL Involved in Melon Fruit Climacteric Behavior and Aroma Volatile Composition

The effect of the QTL involved in climacteric ripening ETHQB3.5 on the fruit VOC composition was studied using a set of Near-Isogenic Lines (NILs) containing overlapping introgressions from the Korean accession PI 16375 on the chromosome 3 in the climacteric 'Piel de Sapo' (PS) genetic background. ETHQB3.5 was mapped in an interval of 1.24 Mb that contained a NAC transcription factor. NIL fruits also showed differences in VOC composition belonging to acetate esters, non-acetate esters, and sulfur-derived families. Cosegregation of VOC composition (23 out of 48 total QTLs were mapped) and climacteric ripening was observed, suggesting a pleiotropic effect of ETHQB3.5. On the other hand, other VOCs (mainly alkanes, aldehydes, and ketones) showed a pattern of variation independent of ETHQB3.5 effects, indicating the presence of other genes controlling non-climacteric ripening VOCs. Network correlation analysis and hierarchical clustering found groups of highly correlated compounds and confirmed the involvement of the climacteric differences in compound classes and VOC differences. The modification of melon VOCs may be achieved with or without interfering with its physiological behavior, but it is likely that high relative concentrations of some type of ethylene-dependent esters could be achieved in climacteric cultivars.

This research was supported by the Ministry of Innovation and Science (at present, Ministry of Economy and Competitiveness) and Regional Development of European Union FEDER funds (AGL2010-20858, AGL2012-40130-C02-02, AGL2003-09175-C02-01, and AGL2003-09175-C02-02), Fundación Séneca de la Región de Murcia (projects 11784/PI/09, 05676/PI/07 and 00620/PI/04), and Consejería de Educación de la Región de Murcia (BIO-AGR06/02-0011). N. Dos-Santos was supported by an FPU-MEC AP2006-01565 fellowship (Ministry of Education, Spain). A. Díaz was supported by a JAE-Doc contract from CSIC.

Peer reviewed