Functional analysis of alpha-DOX2, an active alpha-dioxygenase critical for normal development in tomato plants.
Plant alpha-dioxygenases initiate the synthesis of oxylipins by catalyzing the incorporation of molecular oxygen at the alpha-methylene carbon atom of fatty acids. Previously, alpha-DOX1 has been shown to display alpha-dioxygenase activity and to be implicated in plant defense. In this study, we investigated the function of a second alpha-dioxygenase isoform, alpha-DOX2, in tomato (Solanum lycopersicum) and Arabidopsis (Arabidopsis thaliana). Recombinant Slalpha-DOX2 and Atalpha-DOX2 proteins catalyzed the conversion of a wide range of fatty acids into 2(R)-hydroperoxy derivatives. Expression of Slalpha-DOX2 and Atalpha-DOX2 was found in seedlings and increased during senescence induced by detachment of leaves. In contrast, microbial infection, earlier known to increase the expression of alpha-DOX1, did not alter the expression of Slalpha-DOX2 or Atalpha-DOX2. The tomato mutant divaricata, characterized by early dwarfing and anthocyanin accumulation, carries a mutation at the Slalpha-DOX2 locus and was chosen for functional studies of alpha-DOX2. Transcriptional changes in such mutants showed the up-regulation of genes playing roles in lipid and phenylpropanoid metabolism, the latter being in consonance with the anthocyanin accumulation. Transgenic expression of Atalpha-DOX2 and Slalpha-DOX2 in divaricata partially complemented the compromised phenotype in mature plants and fully complemented it in seedlings, thus indicating the functional exchangeability between alpha-DOX2 from tomato and Arabidopsis. However, deletion of Atalpha-DOX2 in Arabidopsis plants did not provoke any visible phenotypic alteration indicating that the relative importance of alpha-DOX2 in plant physiology is species specific.
Bannenberg
Gerard
G
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain.
Martínez
Marta
M
Rodríguez
María José
MJ
López
Miguel Angel
MA
Ponce de León
Inés
I
Hamberg
Mats
M
Castresana
Carmen
C
D017360:Arabidopsis / Q000235:genetics; D003001:Cloning, Molecular; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D054883:Oxylipins / Q000378:metabolism*; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D054883:Oxylipins; D010940:Plant Proteins; D018749:RNA, Plant; D049308:Dioxygenases