| RACK1gene was discovered in animal for the first time, afterwards, many RACK1ho-mologous genes were found in eucaryon. For mammalian, it is a skeleton protein, which can in-teract with many signal molecules and regulate different signal transduction pathways. On the contrary, plant RACK1was rarely studied, whether is paly the same role as animals is still un-known. However, because of both RACK1amino acid sequence are quite similar and the same domain was found in plant RACK1, so we infer that plant RACK1may have partial functionality of its animal counterpart. Plant RACK1was first found in tobacco suspension cell BY-2as a growth induced genes, and it was proved that it joined plenty plant hormone-related signal transduction pathways subsequently.OsRACK1was first reported in1995. OsRACK1could be induced in rice suspension cell by auxin, abscisic acid (ABA) and methyl jasmonate. OsRACK1protein could be accumulated when rice seeds in imbibition situation. We infer RACK1may regulate the signal pathway through G protein, due to gibberellin, abscisic acid’s role in germination depend on G protein signal pathway. Vice-versa.Based on RACK1interference (RACK1A RNAi), overexpression (OX) and wild type (WT) as materials, different concentration of ABA, H2O2was used during germination. Our study fo-cused on the rice germination under different condition. The expression of RACK1and some enzymes and its ABA, H2O2content were determinated by relative quantitative PCR during ger-mination. For the expection of relationships between RACK1and ABA (other plant hormones) in signal transduction. Lay a solid theory foundation for RACK1in rice germination and its rela-tionships between G protein in signal transduction pathways.Our results are as following:1. Seeds germination process showed that compare with WT and OX, RACK1A RNAi showed a delayed germination. Under exogenous ABA, the germination rate of RNAi decreased dramatically, more sensitive to ABA than WT and OX. RACK1A regulate germination through H2O2could be conclude2. Treated rice seeds with ABA in different concentration, compare to control group, the expression of RACK1A decreased. The expression of RACK1, H2O2content showed a similar trends under exogenous ABA treatment, germination was delayed neither, this effect could be offset by adding exogenous H2O2. Germination was inhibited because of both RACK1and H2O2 (germination promoter) were inhibited. However, exogenous H2O2could offset the difference between different genotype.3. qPCR and the activity of amylase determination showed both of the two amylases of RNAi were lower than WT and OX (in terms of expression and activity), ABA could block ger-mination by RACK1inhibited.4. RACK1A protein was analysed by protein transmembrane analysis software. To our surprise, no transmembrane domain was found, it’s a cytoplasmic protein. YFP-RACK1A was transformed into rice protoplast by protoplast transient expression technique. YFP-RACK1A fluorescence was scattered in whole cytoplasm. That means RACK1A was located in the cyto-plasm.5. ABA and H2O2content was determinated within24h and48h (after germination), the RNAi was much higher than the WT and OX. There’s no significant difference between WT and OX (in terms of ABA). RNAi endogenous H2O2was dramatically lower than WT after24h,48h of germination. OX H2O2content a bit higher than WT, That means ABA was blocked by RACK1A, and H2O2was promotedAbove all, our study found synthetization of ABA in rice can be regulated, germination can be promoted by maintain or increase H2O2content. Furthermore, the expression and activity of amylase was regulated by RACK1either, RACK1can be decreased by exogenous ABA to block germination. That means there’s a complicated signal regulation network between ABA and RACK1. |
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