Identification of candidate genes and proteins for tasseling stage drought tolerance through integrated transcriptomic and proteomic analysis approach in maize

Abstract Drought stress particularly at the tasseling stage is the most devastating abiotic factor and major contributor to yield reduction in maize (Zea mays L.). Despite recent scientific evolution in deciphering maize drought stress responses, the overall picture of key genes and proteins regulating maize tasseling drought tolerant is not understood. In this study, we conducted comparative physiological, transcriptome and proteomic analyses approach to monitor the changes in the leaf tissues of two contrasting hybrid cultivars exposed to drought stress at the tasseling stage. We identified 1701 differentially expressed genes (DEGs) in RNA-sequence runs and 424 differentially expressed proteins (DEPs) from an iTRAQ-based analysis. Mapman analysis revealed that several regulatory processes were influenced by drought conditions, especially signal transduction, cell-wall remodelling, cellular redox homeostasis, and hormone metabolism were observed in both mRNA- and protein-level. However, transcription factor regulation and secondary metabolism were specifically identified at the transcript level, whereas photosynthesis was uniquely identified to be affected by drought stress at the protein level. Meanwhile, a weak correlation between DEGs and DEPs was observed, indicating the drought response of maize at tasseling stage is largely regulated post-transcriptionally. Furthermore, comparative physiological analysis and qRT-PCR results substantiated the trancriptomic and proteomic findings. Additionally, we screened ZmPOD, ZmRAV1, ZmTPP and performed phenotypical and physiological characterizations of transgenic Arabidopsis lines and wild-type. Resultantly, the transgenic Arabidopsis lines exhibited stronger tolerance to drought than the WT. This functional verification reinforces the reliability of our omics-based candidate gene selection. Overall, our research provides an elaborate understanding of drought-responsive genes and pathways mediating maize drought tolerance at the tasseling stage.