Cauliflower mosaic virus 35S (CaMV35S) promoter, long variant
Constitutive promoter derived from Cauliflower mosaic virus (CaMV), driving strong, near-ubiquitous transcription across most dicot plant tissues and developmental stages. This long (835 bp) variant extends past the minimal enhancer-core fragment and serves as the standard reference promoter for plant transformation and transgenic crop research.
Origin: Cauliflower mosaic virus
Characteristics
Deletion analysis maps the essential enhancer to sequences between -343 and -90 relative to the transcription start site; truncating to -90 reduces reporter activity to background levels in tobacco protoplasts, while sequences upstream of -343 add no further increase (Odell et al. 1985). Within this region, subdomain B (-343 to -90) preferentially drives expression in leaves, stems, and cotyledons, and subdomain A (-90 to +8) preferentially drives expression in root and radicle tissue; the two subdomains together give expression detectable in most cell types at all developmental stages examined (Benfey et al. 1989).
Applications: Default constitutive promoter for transgene and reporter gene (GUS, GFP) expression in dicot plants, including herbicide- and pest-resistance traits in transgenic crops and comparative benchmarking of new plant promoter and enhancer constructs.
Limitations: Markedly weaker in monocot species such as rice and maize than in dicots, and largely inactive in pollen; monocot transformation typically substitutes an intron-enhanced 35S derivative or a monocot-native promoter such as maize ubiquitin or rice Actin1.