Ammonium-stress Enhances Biosynthesis Of An-Thocyanin In Apple (Malus Spectabilis)

The biosynthesis of anthocyanin in plant organs is affected by many external and internalfactors, such as light, temperature, UV-B, nutrition and hormones. In this work the influenceof MS medium containing varied concentrations of macronutrients and without ammoniacal(NH4+) nitrogen on in vitro induction of anthocyanin formation and the expression level ofthe structural genes and transcription factors (TFs) involved in anthocyanin biosynthesispathway in the leaf explant tissues of Malus spectabilis were investigated. The result showed：(1) Anthocyans were induced on the low macronutrients concentration and without am-moniacal (NH4+) nitrogen. The lower nitrogen concentrations the mediums contained, themore anthocyans could harvest. As expected, nitrogen stress caused a dramatic increase ofboth anthocyanin accumulation and transcription levels of structure genes involved in antho-cyanin biosynthesis pathway. Meanwhile, MsMYB10, a R2R3MYB transcription factor ho-mologous to known activators for anthocyanin biosynthesis was significantly induced in leaftissues under the ammonium stress condition. We conclude that MsMYB10coordinately re-gulates genes in the anthocyanin pathway and the expression level of this regulator is the ge-netic basis for apple leaf color.(2) Total RNA was extracted from the leaves of Malus.’Red splendor’, and then, ob-tained First-strand cDNA by reverse transcription PCR. The cDNA was used as template toobtain the CDS sequence of the MrMYB10gene by using Original TA Cloning Kit. Fluores-cence real-time PCR was used in this study to test the expression levels of relative structuregenes and TFs of flavonoid pathway. The expression levels of PAL, FGT, CHS, DFR, ANSand FGT in rolling leaf stage, leaf expansion initial stage, the small bud stage and the big budstage were much higher than that in full leaf expansion stage, maturation stage and floweringstage. MrMYB10and bHLH33were the TFs genes shared the same pattern with structuregenes. The expression difference of WD40was small. On the contrary, MYB6was the nega-tive regulatory factor.