Silencing of the LeSGR1 gene in tomato inhibits chlorophyll degradation and exhibits a stay-green phenotype
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The full-length cDNA of LeSGR1 was cloned from tomato by RT-PCR and RACE. The cDNA encoded a protein of 272 amino acid residues and was deposited in GenBank (accession No. DQ100158). Northern analysis suggests that LeSGR1 gene specifically expresses in senescent leaves and mature fruits of tomatoes. Desiccation and flooding induce the expression of LeSGR1 in tomato leaves and stems. Both in ethylene-insensitive mutants (Nr) and ripening inhibitor mutants (rin), the expression of LeSGR1 is markedly decreased compared with that in the wild type. Alignment of the nucleotide sequence of SGR1 cloned from the tomato green flesh (gf) mutant with that from the wild type tomato shows a single nucleotide change leading to an amino acid substitution in gf mutant. Furthermore, LeSGR1 gene silencing by RNA interference results in inhibited chlorophyll degradation similar to the phenotype in gf mutant. Thus, we conclude that LeSGR1 is crucial to chlorophyll degradation and the mutation of SGR1 protein might be responsible for gf tomato properties.
Additional key wordsdesiccation flooding Lycopersicon esculentum mutants senescence
days post anthesis
open reading frame
rapid amplification of cDNA ends
- RT PCR
reverse transcriptase polymerase chain reaction
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This work was supported by the National Natural Science Foundation of China (No.30771464 and No.30871709.) and by China Postdoctoral Science Foundation (No.20060390677 and No.20070420717). We thank Prof. J.R. Botella (University of Queensland) for critical reading of the manuscript.
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