Analysis of the Arabidopsis NAC gene superfamily in plant development

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Title: Analysis of the Arabidopsis NAC gene superfamily in plant development
Author: Alvarado Chavez, Veria Ysabel
Abstract: There are a vast number of transcription factors that regulate plant growth and development . The NAC gene superfamily is one of the largest families of transcription factors in the plant kingdom . NAC gene expression profiles using Affymetrix ATH1 gene chips were obtained for different plant organs : heart embryo , mature embryo , leaf , root and flower . NAC gene expression profiles proved to be very complex , except for one NAC gene detected only in floral tissue , At1g61110 . At1g61110 was shown to be specifically expressed in the anther tapetum of Arabidospis ; therefore , its name was changed to TAPNAC . TAPNAC became the focus of our studies . We identified a tapnac T -DNA knockout (KO ) line , SALK _069450 . A molecular phenotype was observed . Several oligopeptide , sugar and metal transporters were differentially expressed . Coincidentally , a wheat NAC gene , named TaNAM -B1 for its high sequence similarity to ATNAM , TAPNAC and At3g15510 was found to be involved in nutrient remobilization . PHOSPHOLIPASE D ?1 (PLD ?1 ) was also found to be down -regulated in the tapnac KO . PLD ?1 is an enzyme which hydrolyzes phospholipids that are part of tapetal cell membranes and tapetal lipid bodies . Once these tapetal cell structures are disrupted , the secretion of the compounds that form part of the pollen coat (i .e . proteins , flavonoids and lipids ) into the anther locule is facilitated . Promoter deletion analysis using a GUS reporter and later GUS immuno -localization confirmed the findings of Wellmer and others . TAPNAC is a tapetal specific gene . The cis -regulatory sequence that enhances tapetal expression in the TAPNAC promoter was identified . The consensus motif TCGTGT increased tapetal expression of a GUS reporter gene , only when flanked by the TAPNAC minimal promoter region ( -217 bp to +51 bp ) . In summary , TAPNAC transcription factor has been characterized and data indicates that it could play a role in nutrient remobilization from the tapetum to the pollen grains , particularly during late floral stages . Also , important information on tapetal specifcation cis -regulatory sequences was discovered . The consensus motif TCGTGT , present in TAPNAC promoter , was shown to enhance tapetal expression of a GUS reporter gene .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2588
Date: 2009-05-15

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Analysis of the Arabidopsis NAC gene superfamily in plant development. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2588 .

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