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Abstract Detail


Mineral Nutrition

Smith, Aaron P. [1], Deal, Roger B. [1], Meagher, Richard, B. [1].

Chromatin remodeling regulates transcriptional repressors of phosphate starvation responses in Arabidopsis.

Phosphate availability is one of the major constraints to plant growth. Consequently, plants have evolved many biochemical and developmental adaptations to tolerate low phosphate conditions. Numerous genes implicated in these adaptations have been identified, but little is known about their high-level regulation. Nuclear actin-related proteins ARP5 and ARP6 are conserved among all eukaryotes and participate in chromatin remodeling complexes that regulate gene expression. The expression of many phosphate starvation response (PSR) genes was elevated 5- to 50-fold in Arabidopsis arp5-1 and arp6-1 knockout mutants on phosphate sufficient media, paralleling the molecular phenotypes of phosphate-limited wild-type plants. These ARP mutants also showed 10- to 1000-fold reductions in the gene expression of three potential PSR repressors, BT2, BT5, and ZFD. bt2-1 and zfd-1 knockout mutants were de-repressed for many of the same PSR genes as the ARP mutants, consistent with BT2 and ZFD acting as high-level PSR repressors that are regulated by chromatin remodeling. In the arp6-1 mutant, H2A.Z histone variant deposition was disrupted at the BT2 and BT5 loci, indicating that these two BTB/POZ transcription factor genes are primary targets of an ARP6-containing plant SWR1-like complex. In summary, we have identified three novel transcriptional repressors of PSR genes whose expression is positively regulated by ARP-containing chromatin remodeling complexes. These data reveal that the PSR is largely under repressive control, and provide molecular tools for future studies aimed at identifying the cellular phosphate-sensing mechanisms that initiate the PSR.


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1 - University of Georgia, Genetics

Keywords:
Phosphate
Actin-related protein
transcriptional repression
BTB/POZ
histone variant
Arabidopsis.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P11003
Abstract ID:314


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