S17 - Session O1 - CmERFⅠ-2 regulates sucrose accumulation in oriental melon fruit by inhibiting the interaction between CmMYB44 and CmSPS1.

Authors: Hongyan Qi *, Ge Gao, Fan Yang, Cheng Wang

Soluble sugar is critical for fruit ripening and quality formation, but the underlying regulatory mechanisms are largely unknown. Here, high sucrose melon cultivar 'HS' and low sucrose melon cultivar 'LW' fruit were used as the experimental material. We identified a transcriptional repressor, CmMYB44, which transiently expressed in two oriental melon cultivars to explore that CmMYB44 negatively regulated sucrose accumulation and ethylene production, and repressed the expression of CmSPS1 and CmACO1 , key genes in sucrose accumulation and ethylene synthesis. From the pericarp color turning stage onwards, the repressive effect of CmMYB44 on CmSPS1 and CmACO1 is inhibited by CmERFⅠ-2, which expressed higher in 'HS' than that in 'LW'. Our results indicate that CmERFⅠ-2 suppresses CmMYB44 expression; weakens the interaction between CmMYB44 and CmSPS1 and CmACO1 to promote sucrose accumulation. In addition, the repressive effect of CmMYB44 on sucrose accumulation is reduced by ethylene. This study provides new insights into the regulatory mechanisms of sucrose accumulation and sheds light on the interplay between transcription factors during oriental melon fruit ripening and quality formation.