Journal Article

Indirect ABA-dependent Regulation of Seed Storage Protein Genes by FUSCA3 Transcription Factor in <i>Arabidopsis</i>

Yasuaki Kagaya, Rie Okuda, Atsushi Ban, Ryoko Toyoshima, Kumiko Tsutsumida, Haruko Usui, Akiko Yamamoto and Tsukaho Hattori

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 46, issue 2, pages 300-311
Published in print February 2005 | ISSN: 0032-0781
Published online February 2005 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci031
Indirect ABA-dependent Regulation of Seed Storage Protein Genes by FUSCA3 Transcription Factor in Arabidopsis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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The key transcription factors that control seed maturation, ABSCISIC ACID INSENSITIVE3 (ABI3) and FUSCA3 (FUS3), share homologous DNA-binding domains. Regulation of seed storage protein genes At2S3 and CRC by ABI3 and FUS3 was investigated using transgenic plants in which ABI3 and FUS3 could be ectopically induced by steroid hormones. Like ABI3, the presence of FUS3 led to expression of At2S3 and CRC in vegetative tissues. FUS3-mediated induction of CRC was completely dependent on exogenous abscisic acid (ABA), while At2S3 was weakly induced without ABA but strongly enhanced with ABA. This ABA dependency of FUS3-induced CRC and At2S3 expression was similar to that observed for ABI3. However, kinetic analysis revealed distinctions between the mechanisms of ABA-dependent CRC regulation by FUS3 or ABI3, and between target genes. While At2S3 activation by FUS3 was rapid, CRC induction by FUS3 in the presence of ABA, and by ABA followed by the presence of FUS3, took a significantly longer time (24–36 h). This suggested the involvement of an indirect mechanism requiring the ABA- and FUS3-dependent synthesis of intermediate regulatory factor(s). A chimeric protein composed of the FUS3 B3 domain, and a heterologous activation domain and nuclear localization signal exhibited a tight coupling with ABA regulation as observed for wild-type FUS3. Simultaneous induction of FUS3 and ABI3 did not result in the synergistic activation of CRC and At2S3. Based on these results, similarities and differences in the mechanisms of seed storage protein gene regulation by FUS3 and ABI3 are discussed.

Keywords: ABI3; Arabidopsis thaliana; Cruciferin; LEC1; 2S albumin; Seed development; CaMV, cauliflower mosaic virus; Dex, dexamethasone; dHA-His, double hemaglutinin epitope/polyhistidine affinity tag; EST, expressed sequence tag; Estr, estrogen; GVG, glucocorticoid receptor–VP16–GAL4 fusion protein; NLS, nuclear localization signal; RT–PCR, reverse transcription–polymerase chain reaction

Journal Article.  8615 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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