Identification of two new trichome-specific promoters of Nicotiana tabacum.

MAIN CONCLUSION: pRbcS-T1 and pMALD1, two new trichome-specific promoters of Nicotiana tabacum, were identified and their strength and specificity were compared to those of previously described promoters in this species. Nicotiana tabacum has emerged as a suitable host for metabolic engineering of terpenoids and derivatives in tall glandular trichomes, which actively synthesize and secrete specialized metabolites. However, implementation of an entire biosynthetic pathway in glandular trichomes requires the identification of trichome-specific promoters to appropriately drive the expression of the transgenes needed to set up the desired pathway.

Photosynthetic Trichomes Contain a Specific Rubisco with a Modified pH-Dependent Activity.

Ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco) is the most abundant enzyme in plants and is responsible for CO fixation during photosynthesis. This enzyme is assembled from eight large subunits (RbcL) encoded by a single chloroplast gene and eight small subunits (RbcS) encoded by a nuclear gene family. Rubisco is primarily found in the chloroplasts of mesophyll (C3 plants), bundle-sheath (C4 plants), and guard cells.

Accumulation of secreted antibodies in plant cell cultures varies according to the isotype, host species and culture conditions.

Nicotiana tabacum suspension cells have been widely used to produce monoclonal antibodies, but the yield of secreted antibodies is usually low probably because of proteolytic degradation. Most IgGs that have been expressed in suspension cells have been of the human IgG1 isotype. In this study, we examined whether other isotypes displayed the same sensitivity to proteolytic degradation and whether the choice of plant host species mattered.