Abstract/Details

Molecular mechanisms for regulating seed amino acid levels in maize (<i>Zea mays</i>)


2007 2007

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Abstract (summary)

The majority of worldwide maize production is used for food or feed; as such it is imperative that its amino acid balance mirror the needs of humans and animals. However, lysine and methionine, two essential amino acids necessary for proper growth and development, are lacking in the maize endosperm. In this thesis, molecular mechanisms to increase both lysine and methionine deposition in the kernel are explored.

ZmbZIP1, a maize transcription factor, was identified through differential expression in a microarray experiment as a potential candidate to increase the lysine content of the endosperm. ZmbZIP1 was physically mapped to maize chromosome 9, contig 380, and a rice orthologue, RISBZ5 was found through synteny. ZmbZIP1 mRNA was present in all tested maize tissues to varying extents. An attempt to make a ZmbZIP1 knock-down mutant did not result in changes in kernel alpha-zein deposition, the main determinant of endosperm lysine content. These results suggest a functionally redundant protein to ZmbZIP1 exists, the knock-down allele retained sufficient activity to be functional, or phenotypes produced by disruption of ZmbZIP1 are not detectable by current methods.

A molecular mechanism for increasing methionine deposition into maize endosperm was investigated with regards to the 10kDa delta-zein ( Dzs10), a methionine-rich storage protein in endosperm, and cysteine synthase (Cys2), a key regulator in methionine biosynthesis. Dzs10 mRNA was differentially expressed in maize endosperm and a correlation of 0.4535 was found between Dzs10 mRNA and kernel methionine levels, suggesting that a change in Dzs10 expression is partially responsible for kernel methionine deposition. In Cys2 , the level of kernel methionine deposition corresponds to a G/A SNP present in the gene, suggesting different Cys2 alleles may also alter the kernel methionine levels.

Indexing (details)


Subject
Agronomy;
Genetics
Classification
0285: Agronomy
0369: Genetics
Identifier / keyword
Biological sciences
Title
Molecular mechanisms for regulating seed amino acid levels in maize (<i>Zea mays</i>)
Author
Hasenstein, Marie Adams
Number of pages
84
Publication year
2007
Degree date
2007
School code
0097
Source
MAI 46/03M, Masters Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780549335115
Advisor
Scott, M. Paul; Vollbrecht, Erik
University/institution
Iowa State University
Department
Agronomy
University location
United States -- Iowa
Degree
M.S.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
1447529
ProQuest document ID
304854281
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304854281
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