Isolation and analysis of the promoter of IbMYB1 gene from storage roots of purple-fleshed sweet potato

Abstract

In purple-fleshed sweet potato, transcription factors were isolated such as IbMADS10, IbMYB and WD40. IbMYB1 activates the expression of the structural anthocyanin genes and controls anthocyanin biosynthesis specifically in the flesh of storage roots. However, the mechanisms controlling IbMYB1 in underground organs remain unresolved. A 1186-bp promoter sequence of IbMYB1 by hiTAIL-PCR was isolated, the cis-regulatory elements of the promoter sequence were analyzed by using the PLACE and PlantCARE databases. Many cis-regulatory elements associated with sucrose, gibberellins and light were found in the promoter region, such as, SURE1STPAT21, WBOXHVISO1, PYRIMIDINEBOXHVEPB1 and WRKY71OS. The results from GUS histochemical staining indicated that the promoter drove the expression of the reporter gene and induced constitutive GUS expression in all tissues throughout the growth period. The IbMYB1 promoter responses to sucrose, methyl jasmonate and gibberellins treatments. It was obviously up-regulated by 100 μM methyl jasmonate treatment. These results suggest that the ability of plant hormones to modulate the anthocyanin biosynthetic pathway is highly dependent on the IbMYB1 promoter.