Global Transcriptome Changes of Elongating Internode of Sugarcane in Response to Mepiquat Chloride

Abstract

Background: Mepiquat chloride (DPC) is an extensively used chemical to control internode growth and compact canopies in cultured plants. Previous studies suggested that DPC could inhibit gibberellin biosynthesis in sugarcane. Unfortunately, the molecular mechanism underlying the suppressive effects of DPC on plant growth is still largely unknown. Results: In the present study, we first obtained the high-quality long transcripts from internode of sugarcane by PacBio Sequel System. A total of 72,671 isoforms with N50 as 3,073 were generated. These long isoforms were used for the following RNA-seq as reference. Subsequently, short reads generated from Illumina Hiseq 4000 platform were used for comparing the differentially expressed genes in DPC and control groups. The transcriptome profiling showed the 6 days post DPC treatment had the most significant changed genes. These genes were related to plant hormone signal transduction and biosynthesis of several metabolites, indicating DPC affected multiple pathways beside depressed gibberellin biosynthesis. The network of DPC on the key stage was illustrated by weighted gene co-expression network analysis (WGCNA). Among the constructed 36 modules, the top positive correlated module with stage of 6 day post spraying DPC was sienna3. Stf0 sulphotransferase, cyclin-like F-box and HOX12 were the hub genes in sienna3 that had high correlation with other genes in this module. The qPCR demonstrated the high accuracy of RNA-seq result. Conclusion: Taken together, we demonstrated the key role of these genes in DPC-induced growth inhibition in sugarcane.