The Effect of the Site of Nitrogen Assimilation on Plant Growth

In this dissertation, I have explored this question experimentally. My approach was to obtain plants with NO3- reduction mostly in the roots or mostly in the leaves, measure growth and biomass allocation parameters of those plants when grown on NO3-, and compare them to growth of wild-type (WT) plants and nitrate reductase deficient mutants. Two techniques were used to manipulate the site of NO 3- reduction: (i) grafting and (ii) genetic transformation. Grafted wildtype and nitrate reductase-deficient pea plants adapted to changes in the location of NO3- reduction. The results support the idea of rapid mixing of metabolite pools and provide evidence for shoot to root signalling of nitrogen status. Utilizing tissue-specific promoters, plants were created with altered levels of nitrate reductase in roots and shoots. The results showed that transformation of WT plants with nia2 tobacco gene resulted in greater alterations in NRA than the transformation of the corresponding double mutant. Changes in growth and co-suppression-like leaf chlorosis was the most frequent outcome, often causing a lowering or disappearance of NRA. A negative correlation between the ratio of root and shoot reduction of nitrate and the root shoot ratio of transformed plants was found. The possible reasons for differences between the two approaches are discussed.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Lexa, Matej

Contributors dc:contributor

• Cheeseman, John M.

• Agriculture, Agronomy

Language dc:language

eng

Identifier

(MiAaPQ)AAI9921710

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87932