Dynamic Transcriptome Analysis Of Seedling Of Maize Inbreed Line B73 In Response To Chilling Stress

Maize(Zea mays L.),one of most cultivated crops,plays an important role in assuring the food security as well as economy development in China.Maize is very sensitive to low temperature,especially at young seedling stage.Therefore,improve chilling stress tolerance of maize could maize great sense.However,the maize plants act to chilling stress stimuli at transcriptome level still remains largely elusive.In the present study,maize inbred line B73 seedlings were treated with 8 ℃ for up to 96 hours.Young leaves were sampled every 4 hours to access the dynamic changes to chilling stress stimuli.The main results were as following:1.Transcriptome changes as time that exposure to chilling stress differ.There were3 kind of tendency for the dynamic changes of transcriptome.(1)when seedlings were treated less than 8 h,there were much less DEGs,and great proportion of DEGs encodes various kinds of transcription factors;(2)when seedlings were treated under 8 ℃between 12 to 24 h,much more genes were differentially expressed and overwhelmingly larger number of genes were downregulated when compared to upregulated ones;(3)when seedlings were treated longer than 72 h,more genes that were upregulated than downregulated genes;2.A total of 23014 genes expressed among samples,97.53% of which were differentially expressed in at least one comparison.Using Mfuzz software,these expressed genes were dispersed into 16 clusters.Each cluster exhibited unique expression pattern.3.Using Weighted Gene Co-expression Network Analysis method,we found 17 modules that were significantly correlated with exposure time to chilling stress.Salmon module contained 34 genes,including 15 transcription factors,53.33% of genes encoded AP2-EREBP gene family.4.Map Man analysis for these differentially expressed genes revealed that photosynthetic process,synthetic process and metabolism processes were significantly inhibited,however,ROS cleavage and secondary metabolites were invoked,which might contribute to survival of maize seedlings under severe chilling stress.