Abstract
C-repeat binding factors (CBF) are a subfamily of AP2 transcription factors that play critical roles in the regulation of plant cold tolerance and growth in low temperature. In the present work, we sought to perform a detailed investigation into global transcriptional regulation of plant hormone signaling associated genes in transgenic plants engineered with CBF genes. RNA samples from Arabidopsis thaliana plants overexpressing two CBF genes, CBF2 and CBF3, were subjected to Illumina HiSeq 2000 RNA sequencing (RNA-Seq). Our results showed that more than half of the hormone associated genes that were differentially expressed in CBF2 or CBF3 transgenic plants were related to auxin signal transduction and metabolism. Most of these alterations in gene expression could lead to repression of auxin signaling. Accordingly, the IAA content was significantly decreased in young tissues of plants overexpressing CBF2 and CBF3 compared with wild type. In addition, genes associated with the biosynthesis of Jasmonate (JA) and Salicylic acid (SA), as well as the signal sensing of Brassinolide (BR) and SA, were down-regulated, while genes associated with Gibberellin (GA) deactivation were up-regulated. In general, overexpression of CBF2 and CBF3 negatively affects multiple plant hormone signaling pathways in Arabidopsis. The transcriptome analysis using CBF2 and CBF3 transgenic plants provides novel and integrated insights into the interaction between CBFs and plant hormones, particularly the modulation of auxin signaling, which may contribute to the improvement of crop yields under abiotic stress via molecular engineering using CBF genes.
Highlights
Environmental stresses such as low or high temperatures restrain the growth and yield of agriculturally important crops and limit their temporal and spatial distribution (Kasuga et al, 1999)
The Differentially Expressed Genes (DEGs) specially regulated by CBF2 were around two times as many as DEGs specially regulated by CBF3, indicating that CBF2 may control bigger proportion of downstream C-repeat binding factors (CBF) regulon than CBF3, which is in line with the conclusion generated from cold tolerance tests using double and triple cbfs mutants (Zhao et al, 2016)
The key point is how to eliminate the plant growth retardation caused by high expression of CBF genes
Summary
Environmental stresses such as low or high temperatures restrain the growth and yield of agriculturally important crops and limit their temporal and spatial distribution (Kasuga et al, 1999). Many plants possess the ability to survive freezing temperatures, which depends to a large extent on their capacity of cold acclimation (Thomashow, 2010). In addition to increased freezing tolerance, overexpression of CBF genes cause multiple morphological and biochemical changes, including dehydration and high salt stress tolerances (Kasuga et al, 1999), growth retardation, delayed flowering and reduced yields (Liu et al, 1998; Gilmour et al, 2000; Hsieh et al, 2002; Lee et al, 2004; Kasuga et al, 2004; Pino et al, 2008; Tong et al, 2009; Bhatnagar-Mathur et al, 2014), delayed leaf senescence and extended plant longevity (Sharabi-Schwager et al, 2010a,b), and a slight bluish-green tint of leaves (Gilmour et al, 2000). CBF overexpression widely affects plant physiological and developmental processes involving a complex transcriptional regulation system (Kendall et al, 2011; Park et al, 2015)
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