GENETIC MANIPULATION OF STORAGE ROOT DEVELOPMENT IN HORTICULTURAL CROPS

A novel cdc2-like protein kinase gene (Bvcrkl) has been isolated from sugar beet in the Norman Borlaug Institute laboratories. The expression of this gene is associated with dividing tissue, particularly the secondary vascular cambial rings of the sugar beet storage root. This gene is of interest for two reasons. As a plant-specific regulatory protein, it could play an important role in plant development. In addition, the Bvcrkl promoter could be used to regulate transgene expression m order to, for example, modify storage root development. This project centred on the use of transgenic methods to characterise the expression of the Bvcrkl promoter in order to assess its utility for the regulation of transgene expression, as well as providing more insight into the function of the Bvcrkl gene. Sugar beet is notoriously recalcitrant with respect to transformation and regeneration, and an attempt to develop a facile transformation system based on the regenerability of guard cells was unsuccessful. Therefore, two model plant species were chosen as hosts for the Bvcrkl promoter studies, namely tobacco and carrot. The expression of several Bvcrkl promoter fragments fused to the gusA reporter gene was determined throughout the development of transgenic tobacco plants and in carrot storage roots. In order to determine the relationship of Bvcrkl to cell division activity, the expression patterns in tobacco and carrot were compared with those of the Arabidopsis CDC2a, CycB I,· l and ycA2,· l gene promoters. The storage root specificity of Bvcrkl promoter fragments was also compared with the expression of promoter fragments from RSI, a storage root­-specific gene from sugar beet. Transgenic tobacco and carrot plants containing all the promoter constructs of interest were produced. The expression patterns of the Arabidopsis cell cycle promoter construct was consistent with those reported previously. The expression of the Bvcrkl promoter fragments also showed patterns of activity predominantly in tissues undergoing active cell division, including apical and lateral meristems and vascular tissue. In the carrot storage root, the Bvcrkl promoter was expressed in the vascular cambial ring and adjacent vascular tissue. In contrast the RSI promoter was highly expressed throughout the carrot storage root.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

2002

Author dc:creator

• RAHMAN MILAN, A. B. D.

Licence

• https://dora.dmu.ac.uk/bitstreams/317f43d6-ace8-48ed-9604-6666ffa5444d/download