Manipulation of DET1 expression in tomato results in photomorphogenic phenotypes caused by post-transcriptional gene silencing.
The tomato HIGH PIGMENT-2 gene encodes an orthologue of the Arabidopsis nuclear protein DE-ETIOLATED 1 (DET1). From genetic analyses it has been proposed that DET1 is a negative regulator of light signal transduction, and recent results indicate that it may control light-regulated gene expression at the level of chromatin remodelling. To gain further understanding about the function of DET1 during plant development, we generated a range of overexpression constructs and introduced them into tomato. Unexpectedly, we only observed phenotypes characteristic of DET1 inactivation, i.e. hyper-responsiveness to light. Molecular analysis indicated in all cases that these phenotypes were a result of suppression of endogenous DET1 expression, due to post-transcriptional gene silencing. DET1 silencing was often lethal when it occurred at relatively early stages of plant development, whereas light hyper-responsive phenotypes were obtained when silencing occurred later on. The appearance of phenotypes correlated with the generation of siRNAs but not DNA hypermethylation, and was most efficient when using constructs with mutations in the DET1 coding sequence or with constructs containing only the 3'-terminal portion of the gene. These results indicate an important function for DET1 throughout plant development and demonstrate that silencing of DET1 in fruits results in increased carotenoids, which may have biotechnological potential.
Laboratory of Molecular Plant Biology, Stazione Zoologica, Villa Comunale, I-80121 Naples, Italy.
Ganga Rao
GR
Davuluri
Ageeth
A
van Tuinen
Anna Chiara
AC
Mustilli
Alessandro
A
Manfredonia
Robert
R
Newman
Diane
D
Burgess
David A
DA
Brummell
Stephen R
SR
King
Joe
J
Palys
John
J
Uhlig
Henk M J
HM
Pennings
Chris
C
Bowler
D005638:Fruit / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008027:Light; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010860:Pigments, Biological / Q000096:biosynthesis; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified; D034622:RNA Interference
D010860:Pigments, Biological; D010940:Plant Proteins; C118232:tDET1 protein, Lycopersicon esculentum