Clone and function of a glutathione-S-transferase gene from sunflower( Helianthus annuus)

To explore the disease resistance role of a glutathione S- transferases( GST) gene in sunflower,a full- length c DNA of GST( LSK- 2) was cloned based on transcriptome of Helianthus annuus induced by Sclerotinia sclerotiorum. Results showed that the c DNA contained a 675 bp open reading frame( ORF) encoding 224 amino acids. The predicted protein was 55. 45 k Da with isoelectric point of 5. 16. This gene was named as Ha GSTU1( Gen Bank accession No. KR071872). Ha GSTU1 protein contained Tau GST- specific N- terminal domain( G site) and C- terminal domain( H site). Ha GSTU1 was predicted to be a cytoplasmic protein,which shared the highest amino acid identity( 72%) with a GST from Hevea brasiliensis. qRT- PCR results showed that Ha GSTU1 was highly expressed in leaf,and less in sunflower head. Its expression was induced by drought,salt,oxalic acid,S. sclerotiorum and its metabolites. Ha GSTU1 gene was transformed into tobacco by Agrobacterium tumefaciens to further verifying its function. Results showed that expression of Ha GSTU1 improved resistance of transgenic lines to S. sclerotiorum,and significantly increased GST and GPX enzyme activity which were about 2 fold of those under S. sclerotiorum infection. It suggested that Ha GSTU1 gene conferred resistance to S. sclerotiorum.