Phosphate Deficiency Induces Anthocyanin Biosynthesis And Accumulation On Proteome Research In Arabidopsis Thaliana

Environmental factors affect the formation of plant quality by regulating the synthesis of plant secondary metabolites.Anthocyandins,a flavonoid in phenolic compounds,is a water-soluble pigment and is one of the important secondary metabolites of plants.The main factors affecting the synthesis of anthocyanins include light,temperature,sugar,hormones,moisture,nitrogen or phosphorus.Phosphate is an essential nutrient element in plant life cycle.Phosphate deficiency-induced plant anthocyanin accumulation is a model of environmental factors affecting plant secondary metabolism.However,its specific molecular mechanism remains to be further studied.In this study,isobutic markers for relative and absolute quantitation(iTRAQ)were used to study the protein expression profile of Arabidopsis thaliana under phosphorus deficiency conditions,and to identify phosphate deficiency-induced anthocyanin synthesis and Accumulated key proteins(genes);and further stud y the biological functions of these genes(proteins)in the induction and accumulation of anthocyanins in Arabidopsis thaliana by bioinformatics and molecular biology;finally through Arabidopsis thaliana T-DNA insertion mutants further clarify the molecular biological functions of these key genes(proteins),thereby analyzing the molecular mechanism of phosphorus deficiency-induced anthocyanin synthesis and accumulation in Arabidopsis,providing a basis for further understanding of the molecular adaptation of plants to phosphate deficiency The theoretical basis.1.The change of root length,the relative root elongation,the change of phosphate content in roots and aboveground shoots,and the flower in the aerial part of the shoot were examined in the wild type Arabidopsis thaliana(Col-0).The results showed that the roots of Arabidopsis thaliana seedlings growing on the medium lacking phosphate for 7 days had shorter growth and the lower part of the shoots had lower phosphorus content,compared with the seedlings grown on the medium with sufficient phosphorus.The higher content of the hormone indicates that the Arabidopsis thaliana cultured in a medium lacking phosphorus for 7 days can successfully cause changes in the root and anthocyanin accumulation cha racteristic of plant PSRs(Pi starvation responses).2.The protein profile of Arabidopsis thaliana seedlings grown for 7 days on medium with sufficient phosphate(+Pi)or phosphate deficiency(-Pi)was compared by iTRAQ-based proteomic analysis.LC-MS/MS combined with iTRAQ quantitative analysis to obtain significant differentially expressed proteins,and functional analysis of significant differential proteins by bioinformatics and molecular biology.The results showed that we identified a total of 156 significantly differentially expressed proteins(Table 1),and these proteins involved molecular function,defense response,secondary metabolism,protein homeostasis,lipid and amino acid metabolism,carbohydrate metabolism,cellular structure,Signal transduction,transporters and cell growth/development.In addition,phosphorus deficiency activates the Arabidopsis flavonoid biosynthesis pathway at the transcriptional level,and phosphorus deficiency may increase anthocyanin content by promoting flavonoid biosynthesis.3.Five PSR genes in Arabidopsis thaliana under conditions of phosphate deficiency: NPC4(AT3G03530),SQD1(AT4G33030),SQD2(AT5G01220),PAP12(AT2G27190),PHT1;1(AT5G43350)and a flavonoid biosynthesis-related gene DFR(The transcriptional level analysis of AT5G42800)showed that under the condition of phosphate deficiency,the five PSR genes were significantly up-regulated relative to the control group,and the transcription level of DFR was also significantly induced.This observation was consistent with the iTRAQ data(Table 1),indicating that the protein The upregulation is consistent with the increase in transcript abundance.4.The Arabidopsis thaliana T-DNA mutant further clarified the molecular biological function of the key gene(protein)DFR of the flavonoid synthesis pathway by using DFR null mutants(tt3)and wild-type Ler that are defective in anthocyanin biosynthesis,the expression patterns of three upstream genes of PAL1(AT2G37040),PAL2(AT3G53260),and 4CL1(AT1G51680)and three downstream genes LDOX(AT4G22880),AA5GT(AT4G14090),and GSTF12(AT5G17220)were determined.The three upstream genes of DFR were significantly up-regulated in both tt3 and wild-type Ler,and the three downstream genes were up-regulated in wild-type Ler and did not change in the tt3 mutant.It indicated that phosphorus deficiency can successfully initiate the flavonoid biosynthesis pathway,and phosphorus deficiency can enhance the accumulation of anthocyanins by regulating anthocyanin biosynthesis,modification and transport.In summary,phosphate deficiency may enhance the accumulation of anthocyanins by promoting flavonoid biosynthesis.The molecular biological function of related genes(proteins)of the flavonoid synthesis pathway remains to be studied.However,our research further deepens the understanding of the mechanisms involved in the accumulation of anthocyanins induced by phosphate deficiency and the adaptive response of plants to phosphate starvation.