GhGASA14 regulates the flowering time of upland cotton in response to GA3

The gibberellic acid-stimulated Arabidopsis (GASA), a gibberellin-regulated short amino acid family, has been extensively investigated in several plant species and found to be critical for plant growth and development. However, limited research has been reported in cotton. In this study, we identified 38 GhGASAs that were dispersed across 18 chromosomes in upland cotton, and all of these genes had a GASA core domain. Transcriptome expression patterns and qRT‒PCR results revealed that GhGASA9 and GhGASA14 exhibited upregulated expression not only in the floral organs but also in the leaves of early-maturity cultivars. The two genes were further functionally characterized by virus-induced gene silencing (VIGS) and the budding and flowering times after silencing the target genes were later than those of the control (TRV:00). Exogenous application of GA ₃ made the flowering period of the different fruiting branches more concentrated compared with that of the water-treated group (MOCK). Interestingly, allelic variation was detected in the coding sequence of GhGASA14 between early‐maturing and late‐maturing accessions, and the frequency of this favorable allele was greater in high-latitude cotton varieties than in low-latitude ones. Additionally, a significant linear relationship was observed between the expression level of GhGASA14 and flowering time among the 12 upland cotton accessions. Taken together, these results indicated that GhGASA14 may positively regulate flowering time and respond to GA ₃ . These findings could lead to the use of valuable genetic resources for breeding early‐maturing cotton varieties in the future.