Transcriptome analysis to identify candidate genes that response to GA3 and CPPU treatments for mango fruit development

Gibberellin acid (GA₃) and forchlorfenuron (CPPU) are used for the development and expansion of fruits. However, the fruit size, endogenous hormone content and molecular mechanism of mango (Mangifera indica L.) fruit development in response to GA₃ and CPPU treatment are not clear. In this study, mango trees were sprayed with GA₃ and CPPU at four different doses, and a variety of physiological and biochemical indexs were examined. The transcriptomes of mango fruits at different developmental stages were thoroughly examined via transcriptome high-throughput sequencing technology. The results showed that mango fruit increased significantly after GA₃ and CPPU treatment. The contents of GA₃, cytokinin (CTK), indoleacetic acid (IAA) and jasmonic acid (JA) increased in mango pulp under GA₃ and CPPU treatment; however, abscisic acid (ABA) accumulation decreased. These trends align with those of the GA₃ and CPPU treatments, which promoted mango growth and fruit development. The values of 20.00 ∼ 33.33 mg/L GA₃ and 15 mg/L CPPU are the most appropriate. Transcriptome analysis revealed that many differentially expressed genes (DEGs) involved in plant hormone signal transduction are linked to the development and expansion of mango fruits. Additional investigations revealed a number of genes linked to auxin, gibberellin, and fruit expansion, including eleven expansin (EXP) genes, six xyloglucan endotransglycosylase/hydrolase (XTH) genes, six auxin/indole-3-acetic acid (Aux/IAA) genes, two auxin response factor (ARF) genes, one gibberellin 2-oxidase (GA2ox) gene and one gibberellin 3-oxidase (GA3ox) gene. These results shed light on the key genes involved in mango fruit development in response to GA₃ and CPPU treatments and advance our understanding of the molecular mechanisms underlying these treatments.