A bidirectional promoter from Papaya leaf crumple virus functions in both monocot and dicot plants

摘要

The intergenic region of Papaya leaf crumple virus (PaLCrV) transcribes the complementary (C) and virion (V) strand promoters, expressing the C1-C4 and V1-V2 genes respectively in opposite directions. Activities of the bidirectional promoter of PaLCrV in the C and V directions were compared with the 35S promoter of Cauliflower mosaic virus (CaMV35S), using beta-glucuronidase (uidA) as the reporter gene. The resulting promoter constructs were named as pC, pV, and p35S respectively, and transformed into Arabidopsis thaliana, wheat and rice. GUS activity in leaf, stem, root, and flower of Arabidopsis, and the calli of wheat and rice was estimated using histochemical staining, fluorometric assay, and real-time PCR. The expression study showed that the transcription from pC was 12-13 folds higher than that from p35S in root and leaf of Arabidopsis. It expressed at a higher level in root, stem, leaf, flower, and silique of Arabidopsis, and in the callus of wheat and rice, as compared to p35S. The pV also expressed in both monocots and dicots, though the activity was lower as compared to p35S in all the cases. Hence, the C promoter of PaLCrV is a good candidate for high-level expression of transgenes in a wide variety of tissues in dicot and monocot plants.