Exploring Heterosis in Melon (Cucumis melo L.)

Abstract

Heterosis is the superiority of an F1 hybrid over its parents. Since this phenomenon is still unclear in melon, a half diallel experiment based on eight genetically distant breeding lines was conducted in six environments of Central Italy, assessing commercially important traits: yield, total soluble solids (TSS), and days to ripening (DTR). To estimate the additive (general combining ability; GCA) and the non-additive gene effects (specific combining ability; SCA), yield was analyzed by Griffing’s methods two and four, and the results were compared to the GGE (Genotype plus Genotype by Environment interaction) biplot methodology; TSS and earliness were evaluated only by Griffing’s method four. Overall, GCAs were significantly more relevant than SCAs for all examined traits. Least square means (LsM), mid-parent heterosis (MPH), best-parent heterosis (BPH), as well as Euclidean and Mahalanobis’ distances were calculated and compared with the genetic distance (GD). As a few correlations were found statistically significant (only for TSS), it was difficult to predict the value of a hybrid combination only by knowing the genetic distance of its parents. Despite this, heterosis was observed, indicating either the presence of epistatic effects (additive × additive interactions) and/or an underestimate of SCAs embedded within Griffing’s method. The significant Env × Entries source of variation suggests development of hybrids in specific environments. The results are discussed with a breeding perspective.

Nutritional Composition and Health Benefits of Various Botanical Types of Melon (Cucumis melo L.)

“…Melons are members of the Cucurbitaceae family and include many commercially important crops, encompassing diverse botanical/horticultural types that are widely grown across temperate, subtropical, and tropical regions of the world. A recent report on heterosis nature of melons cultivated in Italy suggested that, among eight genetically distinct breeding lines, correlations of TSS value were significantly different, and it was difficult to predict the outcome based on the genetic background of parents [ 3 ]. This work also suggests the significance of breeding line analysis in melons.…”

Underground Heterosis for Melons Yield

“…Hybrid vigor, later termed heterosis to discriminate it from heterozygosity (Shull, 1948), is still intriguing geneticists and is commonly utilized for crop improvement (Duvick, 2001; Hochholdinger and Baldauf, 2018). While yield heterosis was extensively described in multiple plant species, so far it was investigated in a limited number of studies in melon, with variable conclusions regarding its magnitude and breeding impact (Katherine et al , 2011; Pouyesh et al , 2017; Napolitano et al , 2020). In the current study, we initially show that as in other self and cross-pollinated crop plants, there is substantial yield heterosis also in melon.…”

Heterosis goes underground

“…Heterosis has rarely been studied in melon. The few published works include a limited number of crosses between varieties, so general conclusions cannot be drawn (Monforte et al, 2005;Napolitano et al, 2020). Melon germplasm presents a high genetic diversity (Gonzalo et al, 2019), but the exploitation of this variability for hybrid breeding has not been possible.…”