Analysis Of Pollen Specific Elements Of Maize ZmSTK2 Gene Promoter And Its Effect On Lipid Metabolism In Late Pollen Development

Maize(Zea mays L.),the scientific name of maize,gramineae,native to South and Central America,is an important food crop,in the world wide area of cultivation.Whether pollen development is normal during reproductive development directly affects fertilization and fruiting of maize.Therefore,it is of great theoretical and practical significance to study the regulation genes of maize pollen development.A maize pollen abortion mutant zmstk2 was previously identified in the laboratory.The ZmSTK2 gene encodes a receptor-like protein kinase,which is a pollen-specific gene.However,its expression characteristics,cis-acting elements that determine pollen specificity,and the mechanism of ZmSTK2’s influence on pollen development remain unclear.In this study,the expression level of ZmSTK2 gene in maize tassel treated by different factors was analyzed by RT-PCR,and the expression characteristics of this gene were determined.GUS gene expression vectors with different length of promoter fragments were transformed into tobacco,and GUS staining was performed on transgenic tobacco pollen to determine the cis-acting elements of pollen specificity.By comparing the ultrastructure and metabolomics of zmstk2 mutant and wild-type pollen,the effect mechanism of ZmSTK2 on pollen development was clarified.The main results are as follows:(1)PlantCARE website was used to predict the functional elements of ZmSTK2 gene ATG upstream 2143 bp promoter in response to expression patterns.The results showed that the promoter contained elements that responded to abscisic acid,methyl jasmonate and drought.The pollen specific functional element of ATG promoter upstream of ZmSTK2 gene was predicted.The results showed that the promoter contained pollen specific elements of GTGANTG10 and POLLEN1LET52.(2)The expression levels of autin,methyl jasmonate,abscisic acid,salicylic acid,salt solution,PEG6000 and ZmSTK2 gene after high temperature treatment were analyzed by RT-PCR.The results showed that the expression of ZmSTK2 gene was up-regulated by high temperature,drought and methyl jasmonate.Abscisic acid and salicylic acid inhibited the expression of ZmSTK2 gene.The expression of ZmSTK2 gene fluctuated periodically under auxin treatment.High salt treatment had no effect on ZmSTK2 gene expression.(3)GUS expression vector was constructed to drive GUS expression vector and transformed into tobacco.GUS staining results of transgenic tobacco pollen showed that the GTGANTG10 element of ZmSTK2 promoter-1503 to-1153 was crucial and played a leading role in pollen specificity.POLLEN1LET52 elements in-503 to-1 also determined that pollen specificity played a secondary role.(4)The ultrastructure of pollen of zmstk2 mutant showed that starch grains decreased and liposomes increased in pollen at S11 stage,indicating that the mutation of ZmSTK2 gene affected the balance of starch synthesis and lipid metabolism in pollen.Lipid metabolomics analysis revealed abnormal triglyceride metabolism and increased saturated and low unsaturated fatty acid content in pollen of zmstk2 mutant.