| As an important component of biological membrane and nucleic acid,phosphorus is one of the essential elements for plant growth and development.Maize(Zea mays L.ssp.mays)is an important cereal and economic crop worldwide.A large amount of phosphorus fertilizer is needed to ensure the yield during the planting process of corn due to the phosphorus deficiency in nature.The response mechanism of phosphorus deficiency stress is still not well understood.In consideration of the long-term production of maize industry,it is urgent to identify the key regulatory factors and the response mechanism upon phosphorus starvation,so as to improve the utilization efficiency of phosphorus in maize and to cultivate maize varieties resistant to low phosphorus stress.In this study,temporal mRNA and small RNA transcriptome data,spanning three time points,was generatedto comprehensively identify miRNA and key genes involving in responses to low phosphorus stress.The results showed that with the increasing treating time of phosphorus deficiency,the differentially expressed genes in plants increased,and there were more differentially expressed genes in roots than that in leaves.Through the analysis of these differentially expressed genes,it was found that most of them were spatio-temporal specificity,and there was gene enrichment in response to phosphorus deficiency stress among the up-regulated genes in both leaves and roots at the later stage of treatment.Through GO analysis,we found that GO terms enriched in up-regulated genes were mainly associated with mitosis,protein modification,ion binding and response to stress,and the GO terms enriched in the down-regulated genes were mainly related to REDOX,transferase activity,transcription factor activity and heme binding.We have validated the expression of the phosphate-starvation related genes using RT-qPCR.We found many differentially expressed microRNAs in small RNA-seq analysis,among which the up-regulated microRNAs were miR399 and miR827.The downregulated microRNAs were miR156,miR166,miR408,miR444,miR528,etc.Northern blot was employed to validate the most significant repsponsive miRNAs.Then we predicted the target genes of those differential expressed miRNAs,combining with the transciptomic expression patterns.miRNAs and their target genes response to phosphorus deficiency stress identified in this study,may beimportant participants in the response process of maize to phosphorus deficiency stress.It will be very helpful to understanding the relationship between them in illuminating the mechanism of phosphorus starvation tolerance in maize. |
