The present invention comprises the description of a novel regulatory sequence provided to improve the expression of a nucleotide sequence, such as structural genes, in plants, including monocots and dicots. More specifically, the invention refers to regulatory sequences of polynucleotides isolated from cotton plants capable of initiating and activating the transcription of polynucleotides, and to the use of these regulatory sequences for modifying the transcription of endogenous and/or heterologous polynucleotides and the production of polypeptides. The invention further describes DNA constructs that contain the promoter of ubiquitin-conjugation protein coding gene of cotton plants operably linked to a heterologous and/or endogenous gene. Furthermore, the invention provides the use of these constructs in the form of expression vectors, recombinant vectors and in plants, plant cells or transgenic protoplasts. The invention also describes a method using such constructs containing the promoter of ubiquitin conjugating protein coding gene of cotton plants for the production of plants, plant cells or transgenic protoplasts.