Louime, Clifford , Lu, Jiang , Huang, Hong , Uckelmann, Hannah .
Molecular Approaches for Structural Characterization of Chalcone Synthase: cDNA Cloning, Molecular Modeling and Comparative Sequence Analysis among Vitis species.
Chalcone synthase (CHS) operates in the biosynthetic pathway of flavonoids, secondary metabolites involved in the interactions between plants and their environment. This synthase has been shown to play important roles in plant defense mechanism and symbiosis. In flavonoid synthesis, CHS catalyzes the condensation of three acetate residues from malonyl-CoA with 4-coumaroyl-CoA to form naringerin-chalcone, leading to the formation of flavonoids and anthocyanins. CHS expression is regulated by a set of intricate tissue-specific and developmental factors. Abiotic factors, such as nutrient or microorganisms, affect CHS expression. Studies on European grapes have shown that inoculation with specific fungus, such as Plasmopara viticola rapidly induces expression of specific members of the CHS gene family. This de novo synthesis of CHS is in accordance with flavonoid accumulation observed in young leaves following inoculation. Based on these findings, CHS has been used as a marker gene to follow the spatial and temporal effects in plants following fungus infection. In the study presented here, we showed that grapes (Vitis species) CHS genes have a high degree of sequence similarity at the amino acid level (98% homology) and activation of the plant defense-response can be detected by Real-Time PCR though the accumulation of CHS mRNA in Vitis rotundifolia (cv Noble) and Vitis vinifera (cv Cabernet Sauvignon) challenged with Elsinoe ampelina. We also showed through SwissPro computer modeling that CHS is well-conserved among Vitis sp, and that it has a cysteine residue at amino acid 169 that seems to belong to the 4-coumaroyl-CoA binding site and which is required for enzyme activity.
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1 - Florida A&M University, College of Engineering Sciences, Technology and Agriculture, 6505 Mahan Drive, Tallahassee, Florida, 32317, USA
2 - Florida A&M University, Center for Viticulture and Small Fruit Research
3 - Florida A&M University, College of Arts and Sciences - Biochemistry Department
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM