Genetic regulation of Kranz anatomy

Thesis

The C₄ photosynthetic cycle acts to concentrate CO₂ around the enzyme Rubisco. By doing so, C₄ photosynthesis leads to increased radiation, water and nitrogen use efficiencies. As such, C₄ photosynthesis is the most productive form of photosynthesis known. Because it enables such high levels of productivity there are large international efforts to introduce C₄ photosynthesis into non-C₄ crop species such as rice. Kranz anatomy is a characteristic leaf cellular arrangement of concentric rings of bundle sheath and mesophyll cells around closely spaced veins and is crucial to C₄ photosynthesis in almost all known examples. Despite the fact that Kranz has evolved on over 60 times independently little is known about the genetic regulation of Kranz development, as attempts to elucidate Kranz regulators using conventional mutagenesis screens have provided few insights. However, the advent of next generation DNA sequencing technologies has enabled the interrogation of genetic networks at a previously unprecedented scale. The work in this thesis describes a genome-wide transcriptomic analysis of leaf development in maize, a C₄ species, that develops both Kranz-type and non-Kranz-type leaves. Detailed bioinformatics analyses identified candidate regulators of both Kranz development and additional aspects of maize leaf development. Three of the identified Kranz candidates were functionally characterised in both C₄ and non-C₄ species. Furthermore, expression and phylogenetic analyses of GOLDEN2-LIKE (GLK) genes, a small transcription factor family previously implicated in C₄ development in maize, were extended to determine the generality of GLK function in C₄ evolution.

Authors: Fouracre, J

• Publication date: 2013
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: Oxford University, UK
• Language: English
• Keywords: Setaria; rice; C4; leaf development; Kranz; maize; transcriptomics
• Subjects: Cell Biology (plants); Comparative developmental genetics (plants)