Study On The Mechanism Of ZmPLATZ2 Regulating Maize Starch Synthesis

Maize(Zea mays L.)is one of the main food crops in the world,and its yield affects world food security.Corn grain is closely related to corn yield and quality.Starch is the main component of corn kernel,accounting for about 70% of dry weight.At present,the functions of key enzymes in starch biosynthesis are widely studied,but starch biosynthesis is a complex process,and its regulation mechanism remains to be further studied.Studies have shown that transcription factors also participate in the regulation of starch biosynthesis,and partly respond to ABA,sucrose and other signal molecules to regulate starch biosynthesis,but their molecular mechanism remains to be further elucidated.In this study,through co-correlation expression analysis,it was found that transcription factor ZmPLATZ2 had a similar expression profile with the key enzyme gene of maize starch synthesis,suggesting that ZmPLATZ2 might be involved in regulating maize starch synthesis.In this study,the expression pattern of Zm PLATZ gene was analyzed by semi-quantitative RT-PCR and real-time fluorescence quantitative PCR.The characteristics of ZmPLATZ2 gene were analyzed by subcellular localization and yeast self-activation.The mode of interaction between transcription factor ZmPLATZ2 and the promoter of maize starch synthesis key enzyme was further analyzed by yeast single hybridization and instantaneous overexpression of maize endosperm.Meanwhile,ZmPLATZ2 was overexpressed in rice and its function in starch biosynthesis was analyzed.The main results are as follows:1.The expression pattern of target gene ZmPLATZ2 was detected by semi-quantitative PCR and real-time fluorescence.The results showed that the expression level of ZmPLATZ2 gene was high in maize grains and endosperm,and began to be expressed in maize grains at 4days after pollination,and reached the highest expression level in maize grains at 12 days after pollination,and then gradually decreased.Glucose,sucrose and ABA were used to treat endosperm 10 days after pollination.The results showed that glucose had strong up-regulation effect on ZmPLATZ2 gene.2.Subcellular localization and yeast self-activation experiments were used to further analyze the characteristics of transcription factor ZmPLATZ2.The results of subcellular localization showed that transcription factor ZmPLATZ2 was localized in the nucleus,suggesting its transcriptional regulatory function in the nucleus.The analysis of yeast self-activation test results showed that transcription factor ZmPLATZ2 could not activate reporter gene expression and did not have transcriptional activation activity.3.The interaction between transcription factor ZmPLATZ2 and promoters of candidate target genes was analyzed by yeast single hybridization and instantaneous overexpression of maize endosperm.Yeast single hybridization results showed that transcription factor ZmPLATZ2 could directly bind to the promoter of maize starch synthesis gene SS1 in yeast.Transient overexpression of maize endosperm showed that ZmPLATZ2 positively regulated the activity of p Zm SSI promoter.4.Ch IP-q PCR analysis showed that ZmPLATZ2 could bind to the promoter of maize starch synthesis related gene SS1.5.ZmPLATZ2 was overexpressed in rice,and the regulation of exogenous gene ZmPLATZ2 on the expression of key genes for rice starch synthesis was detected.The results showed that the expression levels of SSI,WX and BEIIb genes related to starch synthesis were significantly up-regulated by 3-10 fold in over-expressed ZmPLATZ2 rice.These results indicate that the transcription factor ZmPLATZ2 positively regulates the expression of key genes in starch synthesis in response to glucose signals,which lays a foundation for further research on the starch synthesis and metabolic pathway regulated by maize PLATZ2 transcription factor,and provides a new gene resource for improving maize starch by molecular biological means.