The invention provides transcription factors participating in regulating and controlling synthesis of bitter principles of
cucumis melo and application of the transcription factors. A
comparative genomics method is utilized for the first time, and the two
bHLH transcription factors CmBr and CmBt for controlling synthesis of
bitter taste are discovered in genomes of the
cucumis melo, and separatelycontrol formation of the
bitter taste in roots and wild fruits. Through a
yeast one-
hybrid technology, a gel retardation test and a tobacco transient expression
system, it is proved that the two transcription factors can be directly combined with a
promoter region of a bitter principle synthesis
gene, and then the expression of the synthesis
gene is activated; meanwhile, through transient expression of cotyledons of the
cucumis melo, it is proved genetically that the overexpression of CmBr and CmBt can activate the expression of the
bitter taste synthesis
gene, so that the cotyledons withoutthe bitter taste obtain the
phenotype of the bitter taste. The CmBt gene is located in a
domestication region. The invention further discloses a
molecular mechanism for formation of the bitter taste of the cucumis melo, and a theoretical basis is provided for breeding of the cucumis melo without the bitter taste.