GA₄/GA₇ Deficiency and Downregulated Ent-Kaurenoic Acid Oxidase Impair Seedless Mango Fruit Development

Seedless mangoes are desirable for fresh consumption and processing; however, they frequently exhibit poor fruit development and elevated abscission rates, necessitating applications of fruit regulators, though their physiological and molecular targets remain unclear. In this study, hormonal deficits and regulatory genes associated with mango fruit development were identified. Morphological observations showed that embryo-containing (EC) and embryo-absent (EA) fruits begin to diverge in development between 30 and 45 days after bloom (DAB). During this period, targeted metabolomics of gibberellins (GAs) detected nine GAs; four (GA₂₀, GA₃₄, GA₄, GA₇) behaved consistently across cultivars, with GA₄ and GA₇ showing the largest declines in EA fruit. Applying 50 mg/L GA₃ or GA₄₊₇ at 30 DAB increased fruit growth versus water, with GA₄₊₇ having the greatest effect. Comparative transcriptomic analysis revealed 1476 shared DEGs that were enriched in hormone signaling pathways. Among 13 DEGs involved in GA biosynthesis, KAO (Mi05g23760.1) showed the strongest correlation with GA levels and was markedly downregulated in EA fruits. Together, these results indicate that deficiencies in GA₄/GA₇-potentially resulting from reduced KAO expression-contribute to impaired EA fruit development and that targeted GA₄₊₇ supplementation may more effectively rescue growth than conventional GA₃ treatments. These results provide mechanistic insights and practical guidance for hormone-based strategies to promote consistent development of seedless mangoes, thereby improving yield stability and supporting more sustainable production.