Transcription Analysis Of Gibberellin Metabolism Genes Under The Abiotic Stress Condition In Maize

Gibberellin is an important plant hormone.Recently,some studies proved that some synthetic metabolism and signal genes of gibberellin took part in the process of plant responded abiotic stress.To explore the mechanism of gibberellin synthetic genes under abiotic stresses,digital gene expression(DGE)analysis was performed on maize(Zea mays L.)seedlings subjected to these stresses.On the basis of DGE analysis results,Most of the differentially expressed genes in the diterpenoid biosynthesis pathways were involved in the regulation of gibberellin metabolism.These changes included gibberellin 2-oxidase(GA2ox)genes,which were up-regulated under salt and drought stresses,and gibberellin 3-oxidase(GA3ox)genes,which were down-regulated under these stresses,while the gibberellin 20-oxidase(GA20ox)gene was down-regulated by cold stress.In this study,we also have focused on a group of genes involved in stress responses.These are well-characterised transcription factors,such as DREB,CBF,NAC,b ZIP,MYB,and MYC that play major roles in abiotic stress.DREB/CBF-like genes were significantly up-regulated in response to all three stresses,while MYC factors were consistently down-regulated.On the other hand,the expression of the NAC,b ZIP,and MYB genes were affected in different ways by the three stresses.The four CDPK genes were up-regulated only under cold treatment.In order to study the association between the Zm GA2 oxs and the response under the abiotic stress in maize,we identified 13 maize Zm GA2 ox genes and analyzed their structure and classify by using Rice,Brachypodieae and sorghum GA2 ox as reference.In addition,the polymorphism of these13 Zm GA2 ox was analysed based on the maize Hapmap ? data.Results showed that some SNP were identified in the coding region of these genes.On the basis of maize expression database(Plant Expression Database,www.plexdb.org),we analyzed Zm GA2 ox gene expression patern in the different tissues.To further identified the different function of 13 Zm GA2 ox genes during response to maize drought stress,three maize inbred lines,Zheng58,B73 and Dan340,were treated under drought stress,and analyzed the changes of physiological and biochemical index and the transcription.q RT-PCR results showed that the transcription of some Zm GA2 ox genes were significant changed.Zm GA2 oxs should be associated with the response to drought in maize.Zm GA2ox1;1,Zm GA2ox3;1 and Zm GA2ox9 of maybe play a key role in response to drought stress,because the same transcription regulation were induced in three lines under the drought stress.In this study,we revealed complex changes at the transcriptional level in maize seedlings under different abiotic stresses.Such studies could lead to a better understanding of the genetic basis of the maize response to different environmental stimuli and would be essential for improving the abiotic stress tolerance of maize.In particular,expression changes for the gibberellin(GA)metabolic genes could improve understanding of the molecular basis of the response of the GA pathway to stress conditions.In addition,the results of Zm GA2 ox transcripts were obtained that provide a strong basis for future research on the response to abiotic stress in maize.And a new list of candidate targets for functional studies on genes involved in drought stress has been generated.