A Mutant of Arabidopsis Thaliana Deficient in Chloroplast Dicarboxylate Transport Activity

The photorespiratory pathway in C3 plants is comprised of reactions occurring in three organelles, chloroplasts, peroxisomes, and mitochondria. This pathway therefore provides a unique opportunity for studying transport systems and their role in mediating interactions between organelles. This study is concerned with the characterization and physiological analysis of a mutant of Arabidopsis thaliana (L.) Heyn. defective in dicarboxylate transport across the chloroplast envelope. This mutant was recovered in a screen for photorespiratory mutants and exhibits the growth requirement for high CO(,2) (1% CO(,2), balance air) common to such mutants. This growth requirement is inherited as a simple, recessive, nuclear mutation and the locus defined by this mutation has been designated dct (dicarboxylate transport). Evidence used to support the conclusion that the altered photorespiratory phenotype in the mutant was due to a defect in chloroplast dicarboxylate transport was obtained using both indirect and direct measures of transport. Chloroplast reactions dependent upon transport for a supply of substrates were assayed. Glutamate synthase and glutamate-oxaloacetate aminotransferase were assayed on intact chloroplasts and found missing in the mutant. Transport activity was also measured directly using the silicone oil filter centrifugation technique. Malate, 2-oxoglutarate, glutamate and aspartate uptake were severely reduced or missing in chloroplasts from the mutant.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agronomy

Grantor

University of Illinois at Urbana-Champaign

Date dc:date

10000-01-01

Author dc:creator

• Somerville, Shauna Christine

• Biology, Plant Physiology

Identifier

(UMI)AAI8203598

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71571