Promoter Deletion Analysis of Xylem Cysteine Protease 2 (XCP2) in Arabidopsis thaliana

The process of xylem tracheary element differentiation involves the coordination of vascular cambium activity, cell fate determination, cell expansion/elongation, secondary wall synthesis, programmed cell death, and cellular autolysis. The end result of tracheary element differentiation is a cellular corpse lacking a protoplast and consisting of a thickened cell wall composed mostly of lignin and cellulose. Little is known about the genetic mechanisms regulating the process of tracheary element differentiation. XCP2 expression localizes to tracheary elements according to two independent methods of analysis: promoter reporter experiments and immunogold localization by electron microscopy. XCP2 may be involved in catalyzing the degeneration of the protoplast during the final autolytic stages of tracheary element differentiation. To this date XCP2 function has not been directly demonstrated. In principle, any tracheary element-specific markers can be linked to upstream regulatory genes with roles in tracheary element differentiation. To develop the XCP2 promoter as a tool for identification of transacting factors, a promoter deletion analysis was carried out. Utilizing information from 5â and 3â deletion constructs, a 70-bp region upstream of the XCP2 translational start site is both necessary and sufficient for TE-specific expression of the UidA reporter gene. Mutational analysis of the ACTTTA element at position -113-bp strongly suggests it is a cis element required for XCP2 expression. In silico analysis of an 18-bp promoter region located within 200-bp of the translation start site and including the ACTTTA element revealed high indentity shared between xylem-specific XCP2 homologs from Zinnia elegans, Populus trichocarpa, and XCP1 from Arabidopsis thaliana.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Horticulture

Department dc:contributor.department

Horticulture

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2007

Author dc:creator

• Petzold, Herman Earl III

Chair dc:contributor.committeechair

• Beers, Eric P.

Committee members dc:contributor.committeemember

• Welbaum, Gregory E.
• Nowak, Jerzy

• tracheary element
• Arabidopsis thaliana
• cysteine protease
• promoter deletion
• xylem

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-05112007-152300

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/32582