CHALCONE SYNTHASE FROM CAMELLIA-SINENSIS - ISOLATION OF THE CDNAS ANDTHE ORGAN-SPECIFIC AND SUGAR-RESPONSIVE EXPRESSION OF THE GENES

Three full-length cDNAs (CHS1, CHS2 and CHS3) encoding chalcone syntha se (CHS; EC 2.3.1.74) were isolated from young leaves of Camellia sine nsis. Each cDNA encoded 389 amino acid residues, which showed 93-96% i dentity to one another. Oligonucleotides were synthesized on the basis of the 5'-untranslated sequences of the cDNAs and their corresponding transcripts could be distinguished. The CHS1, CHS2 and CHS3 transcrip ts were abundant in the leaves and stems. After an initial treatment w ith water in darkness, the transcripts fell to very low levels in the young leaves. These levels were increased by a subsequent treatment wi th fructose, sucrose or maltose in darkness, and they increased still further upon a treatment with glucose, sucrose or maltose under contin uous light. These results indicate that the CHS1, CHS2 and CHS3 transc ripts are expressed in various organs and respond to sugars in young l eaves in a similar manner. The effect of continuous light is also disc ussed.