Cloning And Functional Study Of ZmWRKY92 Gene In Maize

As the first grain crop in China,the yield of corn is related to the national food security issue.Plant height is an important agronomic characteristic in modern maize breeding.Appropriate plant height can enhance the lodging resistance of crops,increase the planting density and harvest index of crops,and thus contribute to stable and increased yields.Recent studies have shown that the WRKY transcription factor family is not only involved in the regulation of plant biological and abiotic stresses,but also plays an important role in plant growth and development and plant height morphogenesis.In this study,a height-related WRKY family gene ZmWRKY92 was cloned from maize and its molecular characteristics and biological functions were investigated.The main research results are as follows:1.The coding region of the ZmWRKY92 gene is 1497 bp and encodes 498 amino acids.The ZmWRKY92 protein contains two conserved WRKY structural domains and two C2H2-type zinc finger structure,and the results indicate that ZmWRKY92 is a member of subfamily I.2.The results of tissue expression pattern showed that ZmWRKY92 was highly expressed in stems and leaves.The results of hormone-induced expression pattern showed that the expression level of ZmWRKY92 changed under the treatment of EBR,IAA and GA₃respectively.3.Subcellular localization assays showed that ZmWRKY92 protein was localized in the nucleus.The transcriptional activity of ZmWRKY92 in yeast showed that ZmWRKY92 had transcriptional activity in yeast,and further experiments showed that its transcriptional activity region was located at the N-terminal and C-terminal.The results of the dual luciferase reporter gene assay and yeast single hybridization assay showed that ZmWRKY92could specifically bind the W-box cis-acting elements.4.Plant phenotype analysis showed that maize wrky92 mutant was significantly shorter than wild type B73 maize after jointing stage,and its grain size and 100 grain weight were smaller than those of wild type.Paraffin sections of stem node tissue showed that the semi-dwarf phenotype of wrky92 mutant was caused by the reduction of internode cell volume.5.The results of endogenous hormone assay showed that both GA₃and IAA contents in maize wrky92 mutant were significantly lower than those in wild type.6.Transcriptome sequencing analysis combined with q RT-PCR validation of wild-type B73 and maize wrky92 mutant showed that the mutation of ZmWRKY92 resulted in a significant change in the expression of height-related genes in maize.7.Promoter region binding characterization experiments showed that ZmWRKY92 is an upstream transcriptional regulator of GA synthesis-related genes Zm00001eb175950 and Zm00001eb280200.In conclusion,the height-related maize mutant wrky92 was identified from the EMS mutant library in this study,and further study revealed that the semi-dwarfing phenotype of maize mutant wrky92 was caused by the shortening of plant internode,and ZmWRKY92affects the plant height phenotype of maize plants by regulating GA synthesis pathway.The results of this study provide theoretical reference for exploring maize plant height-related genes and breeding germplasm resources of dwarf maize.