Seasonal effects on flesh volatile concentrations and texture at harvest in a near-isogenic line of melon with introgression in LG X

A melon non-climacteric near-isogenic line (NIL) SC10-2 and its parental ‘Piel de Sapo’ (PS) line were studied in two different seasons to analyse the seasonal effects of an introgression (located in LG X) on texture and aroma volatiles at harvest. Several univariate and multivariate statistical techniques were used to determine the association between the aroma volatile levels and differences in melon texture. Three methodologies involving different treatments of null values were applied to analyse the effects of introgression on volatile organic compounds (VOCs). Substitution of the zeros with the minimum value of the same VOC variable per season and line is proposed for the analysis of VOC data. SC10-2 showed higher whole fruit hardness, flesh firmness, and fibrousness, but lower juiciness than PS. One hundred sixteen VOCs were identified to evaluate the introgression effect, in which 60 VOCs were detected in two seasons with very different climatic conditions during fruit set and ripening; twenty-eight VOCs were involved in the differences on aroma production in the comparison of the NIL SC10-2 with PS. The environmental effects were more significant than the introgression effect. The environment particularly affected VOCs rather than textural traits, and at least one potential VOC quantitative trait locus (QTL) located in LG X alone and another interacting with the environment are proposed to affect VOC fruit metabolism.