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245 1 0 _aFine control of caffeine biosynthesis in tissue cultures of Camellia sinensis
490 0 _vPhytoChemistry Letters, 1(4), p.195-198, 2008
520 3 _aTo determine whether caffeine biosynthesis is controlled by the availability of purine precursors and/or methyl-donors, we examined the effect of some purine compounds on purine alkaloid accumulation, using tea callus cultures. No stimulation of caffeine biosynthesis was observed when the calli were cultured with 0.5 mM adenosine, guanosine or hypoxanthine for 3 weeks. However, 0.5 mM paraxanthine doubled the caffeine level relative to controls. Adenosine stimulated the growth of callus and reduced the caffeine concentration 3 months after inoculation. These results indicate that methylation of xanthosine by 7-methylxanthosine synthase is the most plausible rate-limiting step of caffeine biosynthesis; the supply of non-methylated purine precursors or availability of S-adenosyl-Lmethionine are not the principal controlling factors of caffeine biosynthesis. Adenosine salvage to adenine nucleotide synthesis may contribute to the growth of tea calli, but not to caffeine biosynthesis.
650 1 4 _aCAMELLIA SINENSIS
650 1 4 _aTHEACEAE
650 1 4 _aTEA
650 1 4 _aTISSUE CULTURE
650 1 4 _aBIOSYNTHESIS
650 1 4 _aCAFFEINE
650 1 4 _aPARAXANTHINE
650 1 4 _aPURINE NUCLEOSIDE
650 1 4 _aPURINE BASE
700 1 2 _aDeng W.W.
700 1 2 _aLi, Y.
700 1 2 _aOgita, S.
700 1 2 _aAshihara, H.
856 4 0 _uhttps://drive.google.com/file/d/1n_k0Lk4buBkY2klT-FyCUtxRXtDYwXXc/view?usp=drivesdk
_zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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