title: A nuclear gene for the iron-sulfur subunit of mitochondrial complex II is specifically expressed during Arabidopsis seed development and germination.
abstract: Three nuclear genes, SDH2-1, SDH2-2 and SDH2-3, encode the essential iron-sulfur subunit of mitochondrial complex II in Arabidopsis thaliana. SDH2-1 and SDH2-2 probably arose via a recent duplication event and we reported that both are expressed in all organs from adult plants. In contrast, transcripts from SDH2-3 were not detected. Here we present data demonstrating that SDH2-3 is specifically expressed during seed development. SDH2-3 transcripts appear during seed maturation, persist through desiccation, are abundant in dry seeds and markedly decline during germination. Analysis of transgenic Arabidopsis plants carrying the SDH2-3 promoter fused to the beta-glucuronidase reporter gene shows that the SDH2-3 promoter is activated in the embryo during maturation, from the bent-cotyledon stage. beta-Glucuronidase expression correlates with the appearance of endogenous SDH2-3 transcripts, suggesting that control of this nuclear gene is achieved through transcriptional regulation. Furthermore, progressive deletions of this promoter identified a 159 bp region (-223 to -65) important for SDH2-3 transcriptional activation in seeds. Interestingly, the SDH2-3 promoter remains active in embryonic tissues during germination and post-germinative growth, and is turned off in vegetative tissues (true leaves). In contrast to SDH2-3 transcripts, SDH2-1 and SDH2-2 transcripts are barely detected in dry seeds and increase during germination and post-germinative growth. The opposite expression patterns of SDH2 nuclear genes strongly suggest that during germination the embryo-specific SDH2-3 is replaced by SDH2-1 or SDH2-2 in mitochondrial complex II.
authors.affiliation: Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Casilla 114-D, Santiago.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Elorza
authors.forename: Hannetz
authors.initials: H
authors.lastname: Roschzttardtz
authors.forename: Isabel
authors.initials: I
authors.lastname: Gómez
authors.forename: Armand
authors.initials: A
authors.lastname: Mouras
authors.forename: Loreto
authors.initials: L
authors.lastname: Holuigue
authors.forename: Alejandro
authors.initials: A
authors.lastname: Araya
authors.forename: Xavier
authors.initials: X
authors.lastname: Jordana
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination / Q000235:genetics; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D045332:Photosystem II Protein Complex / Q000235:genetics; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000254:growth & development; D013385:Succinate Dehydrogenase / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D007506:Iron-Sulfur Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D018749:RNA, Plant; C496078:SDH2-1 protein, Arabidopsis; C496079:SDH2-2 protein, Arabidopsis; C496080:SDH2-3 protein, Arabidopsis; D013385:Succinate Dehydrogenase