Polyploidy Promotes Larger Mango Fruits with Cultivar-Specific Quality Changes

Polyploidy is widely used in plant breeding to generate novel phenotypes and improve agronomic traits, often promoting organ enlargement through the so-called “gigas effect.” However, in mango (Mangifera indica L.), the effects of genome duplication on fruit quality are still poorly understood. This study evaluated the effects of polyploidy on fruit morphology and physicochemical traits by comparing diploid (2n) and autotetraploid (4n) genotypes of six polyembryonic cultivars grown under identical field conditions. Autotetraploids consistently produced larger and heavier fruits across all cultivars, with significant increases in length, width, thickness, and especially fruit weight, confirming a strong and uniform size-enhancing effect of genome duplication. In contrast, quality-related traits showed cultivar-specific responses. Fruit firmness was not significantly affected by ploidy level, while penetration hardness differed only in ‘Kensington Pride’. Total soluble solids decreased in autotetraploids of ‘Kensington Pride’ and ‘Gomera 1’, whereas titratable acidity increased in ‘Kensington Pride’ and ‘Mun’ autotetraploids. These results indicate that autopolyploidization consistently enhances fruit size in mango (e.g., fruit weight increased up to twofold in some cultivars); however, its effects on key quality traits such as soluble solids and acidity are cultivar-dependent, and should therefore be carefully considered in breeding programs.