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Abstract Detail


Metabolism

Ding, Geng [1], Che, Ping [2], Ilarslan, Hilal [3], Wurtele, Eve [3], Nikolau, Basil J [4].

Molecular genetic studies indicate that maternal mitochondrial leucine catabolism is required for normal seed development in Arabidopsis thaliana.

3-Methylcrotonyl-CoA carboxylase (MCCase) is a nuclear-encoded, mitochondrial-localized biotin-containing enzyme that is required for leucine catabolism, and it may also play important roles in the catabolism of isoprenoids and in the mevalonate shunt. In Arabidopsis, two MCCase subunits (the biotinylated MCCA subunit and the non-biotinylated MCCB subunit) are each encoded by single genes (At1g03090 and At4g34030, respectively). Reverse genetic approach has been undertaken to dissect the physiological role of MCCase in plants. We have recovered and characterized T-DNA knock-out alleles of MCCA and MCCB genes. Metabolite profiling studies indicate that mutations in either MCCA or MCCB genes block mitochondrial leucine catabolism, as inferred from the increased accumulation of leucine. This biochemical block is associated with an impaired reproductive growth phenotype, which includes aberrant flower and silique development, and decreased seed germination. The decreased seed germination phenotype is only expressed when homozygous mutant seeds are collected from a mother that is itself homozygous, but not when collected from a mother that is heterozygous. These observations indicate that maternal mitochondrial leucine catabolism is required for normal seed development. Additional biochemical characterizations of the mcca and mccb mutant stocks are being conducted to understand the relationship between the phenotype and leucine and/or isoprenoids metabolism. These characterizations are providing new insights into the role of catabolic processes in growth and development, an area of plant biology that is poorly understood.


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1 - Iowa State University, Department of Biochemistry, Biophysics and Molecular Biology, Ames, IA, 50011
2 - University of Western Australia
3 - Iowa State University, Department of Genetics, Development and Cell Biology
4 - Iowa State University, Department of Biochemistry, Biophysics and Molecular Biology

Keywords:
Biotin
Leucine catabolism
Methylcrotonyl-CoA carboxylase
T-DNA knock-out allele.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P19037
Abstract ID:1748


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