The Role of Acyl Carrier Protein Isoforms in Determining Plant Lipid Content and Composition

Acyl carrier protein (ACP) is a small protein that is a critical cofactor for fatty acid biosynthesis in all organisms. ACP carries growing acyl chains through all of the enzymatic steps in fatty acid biosynthesis. Acyl-ACP's are also the substrate for stearoyl-ACP desaturase and plastid acyltransferase reactions. Multiple isoforms of ACP are found in all higher plants. These isoforms differ in expression in various tissues and organs, and they also differ in the timing and regulation of expression during plant growth and development. The reason for the diverse number of ACP isoforms in plants is not understood. One of the goals of this research was to better understand the role of ACP isoforms in plant fatty acid biosynthesis. In addition, since ACP is critical for fatty acid biosynthesis, a second goal of this research was to inhibit fatty acid biosynthesis in oilseeds through antisense ACP expression in order to gain a better understanding of how oilseeds regulate the partitioning of carbon between storage components. Four different sets of transgenic Arabidopsis plants were generated. In the first set of transgenic plants, ACP1, a prominent seed ACP isoform, was overexpressed in leaf tissue. This resulted in alterations in the fatty acid composition of the leaf tissue, and provided in vivo evidence that ACP isoforms may influence fatty acid composition. The second set of transgenic plants were transformed with antisense ACP4, the major leaf isoform. Reduction of this ACP isoform in leaf tissue resulted in significant reductions in lipid content, altered fatty acid composition, and affected plant photosynthesis, growth, and development. The third and fourth sets of transgenic plants were transformed with antisense ACP1 and ACP2 using a seed-specific promoter. These plants had reduced seed lipid content ranging from 5 to 40%, but there were no resulting alterations in fatty acid composition or seed protein content. These studies have demonstrated that ACP isoforms may play a role in determining lipid fatty acid composition. In addition, antisense ACP expression appears to be effective at reducing seed lipid content without affecting protein content.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Food Science and Human Nutrition

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Branen, Jill Kristine

Contributors dc:contributor

• Engeseth, Nicki J.

• Agriculture, Food Science and Technology

Language dc:language

eng

Identifier

(MiAaPQ)AAI3069975

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83676