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Dissertation/Thesis Abstract

Evolution of barren STALK2/LAX PANICLE2 (BA2/LAX2) in angiosperms
by Wardell, Brian, M.S., California State University, Long Beach, 2013, 67; 1527423
Abstract (Summary)

Much of plant growth is directly or indirectly regulated by the plant hormone auxin. Although some genes involved in the auxin pathway have been characterized, there are still gaps in our knowledge of this genetic pathway. Recently, the orthologous maize genes BARREN STALK2 ( BA2) and rice gene LAX PANICLE2 (LAX2) have been cloned and characterized. Maize ba2 and rice lax2 mutant plants both show significant flaws in axillary meristem (AM) initiation, suggesting a role in auxin regulation. In support of this hypothesis, LAX2 interacts with the auxin regulating LAX PANICLE1 (LAX1) protein. My research reconstructs the evolutionary history of the BA2/LAX2 lineage and tests for conservation of BA2/LAX2 mRNA expression in diverse grasses. My results indicate that the BA2/LAX2 gene family—comprising BA2 /LAX2, BA2/LAX2-Like1 (BA2/LAX2L1), and BA2/ LAX2-Like2 (BA2/LAX2L2)—is restricted to monocots, and shows evidence of two independent gene duplication events. During its evolution, the BA2/LAX2 gene family appears to have gained a PDZ Protein Binding motif, which may allow it to interact with other proteins besides BA1/ LAX1. My expression analyses show that BA2/ LAX2 genes are expressed during multiple stages of inflorescence development, and this expression is conserved across multiple grass species. A unique floral expression pattern appears to have evolved at the base of the Joinvilleaceae lineage. My study further supports the hypothesis that BA2/LAX2 genes are functioning in multiple AM pathways.

Indexing (document details)
Advisor: Malcomber, Simon
School: California State University, Long Beach
School Location: United States -- California
Source: MAI 52/05M(E), Masters Abstracts International
Subjects: Plant biology, Genetics, Evolution and Development
Publication Number: 1527423
ISBN: 978-1-303-76698-5
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