Isolation and functional characterization of seed-specific FAD2-1 promoter from cotton (Gossypium hirsutum L)

Using the high-efficiency thermal asymmetric interlaced PCR technique, a 1,279 bp fragment of 5'-flanking region of the (Delta 12)-desaturase enzyme gene FAD2-1 from Gossypium hirsutum (GhFAD2-1), was successfully isolated. Cis-acting elements search in the fragment revealed the presence of a numbers of tissue-specific motifs including E-box (CANNTG) and -300 element (TGHAAARK). Functional analysis in transgenic Arabidopsis plants showed the 1,279 bp fragment could drive beta-glucuronidase (GUS) reporter gene to express exclusively in seeds. Moreover, the GUS activity was detected mainly in the mid- and late-developmental phases of the developing seeds of transgenic plants. Compared to the developing seeds of the plants having GUS with 35S promoter, seeds of the transgenic plants having GUS with GhFAD2-1 promoter, the later has lower GUS activity. The GhFAD2-1 promoter-driven GUS expression has obvious tissue and developmental stage specificity, which could be applicable to the modification of seed phenotypes of transgenic plants. The results also established the first step toward our understanding of the spatial and temporal regulation mechanisms of the GhFAD2-1, playing a major role in controlling conversion of oleic acid to linoleic acid in the cottonseed.