GENE ACTIVATION IN LIGNIN BIOSYNTHESIS: PATTERNS OF PROMOTER ACTIVITY OF A TOBACCO CINNAMYL-ALCOHOL DEHYDROGENASE GENE

Cinnamyl-alcohol dehydrogenase (CAD) is the penultimate enzyme in lignin biosynthesis.
We have isolated a genomic DNA clone encoding a tobacco CAD and have identified four introns in the coding sequence.
Approximately 2.6 kb of available promoter sequences have been transcriptionally fused to the -glucuronidase (GUS) reporter gene and introduced into the tobacco genome via Agrobacterium-mediated gene transfer.
Fluorometric assays of independent transformants showed GUS activity to be highest in roots, followed by stems and leaves.
Histochemical staining by X-gluc indicates strong expression in the vascular system of stems and leaves preferentially in the developing xylem.
GUS expression was also seen in trichomes.
In experiments performed so far on wound-related expression of GUS in stems and leaves no appreciable enhancement of GUS activity was observed.
However, infection of leaves by fungi did induce strong local GUS activity at the infection sites.
The involvement of this single CAD gene in both developmental and defense-related lignification is discussed.

International Symposium on Natural Phenols in Plant Resistance

M. H. Walter, J. Schaaf, D. Hess

Gene structure, gene fusion, transgenic plants, Nicotiana tabacum, β-glucuronidase, histochemical staining

https://doi.org/10.17660/ActaHortic.1994.381.16