Transcriptome analysis of responses in Brachypodium distachyon overexpressing the BdbZIP26 transcription factor

Authors: Martin, Ruth; KRONMILLER, BRENT - Oregon State University; Dombrowski, James

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2020
Publication Date: 4/21/2020
Citation: Martin, R.C., Kronmiller, B.A., Dombrowski, J.E. 2020. Transcriptome analysis of responses in Brachypodium distachyon overexpressing the BdbZIP26 transcription factor. Biomed Central (BMC) Plant Biology. 20:174. https://doi.org/10.1186/s12870-020-02341-3.
DOI: https://doi.org/10.1186/s12870-020-02341-3

Interpretive Summary: Stresses from disease, pests and environmental conditions are the major cause of reduced growth, persistence and yield in agriculture. Over the past decade, research on plants with altered expression of stress related genes have lead to a better understanding of how plants tolerate stress. Identification and overexpression of the proteins that regulate the expression of genes involved in multiple stresses in plants may be valuable for crop improvement, but could also lead to deleterious effects during normal plant growth. Our investigation of a model grass overexpressing one of these regulatory proteins affected growth in a negative way, producing plants with a reduced stature and activating multiple stress related pathways.

Technical Abstract: Biotic and abiotic stresses are the major cause of reduced growth, persistence and yield in agriculture. Identification of transcription factors that are involved in multiple stresses may be valuable for crop improvement, but may also lead to deleterious effects during normal plant growth and development. To gain a better understanding of the role of BZIP proteins in stress adaptation, we developed transgenic Brachypodium distachyon plants overexpressing BdBZIP26, a gene that was previously shown to be differentially regulated in response to multiple stresses. Brachypodium distachyon overexpressing the BdBZIP26 gene under the control of ZmUbi promoter showed reduced stature compared to WT plants under normal growing conditions. RNA-Seq analysis comparing WT and BdBZIP26 transgenic plants revealed 3579 up- and 4193 down regulated differentially expressed genes (DEGs). Of these DEGs, 438 of the down- and 549 of the up-regulated genes were differentially expressed in all three transgenic lines. Many of these DEGs are similar to those often observed in response to abiotic and biotic stress, including signaling proteins such as kinases/phosphatases, calcium/calmodulin related proteins, oxidases/reductases, transcription factors, as well as disease responsive proteins. Interestingly, we observed in the transgenic plants a strong emphasis on proteins that may indicate cellular instability due to increase of genes associated with protein turnover including ubiquitin-related proteins, U-box related proteins, membrane proteins, and ribosomal synthesis proteins. Transgenic and control plants were exposed to salinity stress. Surprisingly, the analysis of the unique WT DEGs in salt treated plants were found to be the same as 40% of the down- and 46% of the up-regulated DEGs found in the untreated TR lines. This suggests that the over-expression of this transcription factor is placing the plant in a state of stress, which may contribute to the plants diminished stature.