title: ABA-HYPERSENSITIVE BTB/POZ PROTEIN 1 functions as a negative regulator in ABA-mediated inhibition of germination in Arabidopsis.
abstract: To elucidate the contribution of CRL3-ABA-mediated responses, we attempted to find CRL3 substrate receptors involved in ABA signaling. One gene named ABA-HYPERSENSITIVE BTB/POZ PROTEIN 1 (AHT1) was upregulated more than 2.5 times by ABA, and its coding region possessed a BTB/POZ domain, which is the common feature of CRL3 substrate receptors. Loss of AHT1 led to retardation of the germination process, not inhibition of root growth. AHT1 transcripts also increased in response to mannitol, NaCl and drought treatments at the seedling stage and in dry seeds. High expression of AHT1 in dry seeds was inhibited by the defect of ABA signaling components such as ABI1, ABI3 and SRKs indicating that the expression of AHT1 is dependent on ABA signaling. Among bZIP transcription factors participating in ABA signaling, the losses of ABI5/DPBF1, AREB1/ABF2, EEL/DPBF4 and DPBF2/bZIP67 resulted in reduced AHT1 expression, showing that these transcription factors play a positive role in ABA-induced AHT1 expression. While loss of AHT1 did not affect the expression pattern of NCED3, ABI2, SRKs and AREB/ABF genes, it led to hyperinduction of ABI5/DPBF genes such as ABI5/DPBF1, EEL/DPBF4 and AREB3/DPBF3, which are mainly involved in seed development and germination, as well as ABA-inducible genes transactivated by ABI5. Overall, these findings indicate that AHT1 negatively regulates ABA-mediated inhibition of germination, possibly by repressing the expression of a subset of ABI5/DPBF subfamily genes, and that AHT1 may be regulated by a negative feedback process through its linkage with a part of ABI5/DPBF proteins.
authors.affiliation: Department of Biology Education, Pusan National University, Pusan, 609-735, Korea.
authors.forename: Hani
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Biology Education, Pusan National University, Pusan, 609-735, Korea.
authors.forename: Soon-Hee
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Dong Hye
authors.initials: DH
authors.lastname: Seo
authors.affiliation: Underwood International College, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Sunglan
authors.initials: S
authors.lastname: Chung
authors.affiliation: Department of Biological Sciences, Pusan National University, Pusan, 609-735, Korea.
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Bionanotechnology Research Center, Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-806, Korea.
authors.forename: Jeong-Soo
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Woo Taek
authors.initials: WT
authors.lastname: Kim
authors.affiliation: Department of Biology Education, Pusan National University, Pusan, 609-735, Korea. jhlee72@pusan.ac.kr.
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D018525:Germination / Q000187:drug effects / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: C409743:ABI5 protein, Arabidopsis; C500133:AREB3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C107885:DPBF-2 protein, Arabidopsis; D010940:Plant Proteins; D000040:Abscisic Acid; D049308:Dioxygenases; C109043:9-cis-epoxy-carotenoid dioxygenase
keywords: ABA; ABI5/DPBF; AHT1; Arabidopsis; CRL3