Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants

Abstract

Brassinosteroids (BRs) are growth-promoting plant hormones that play a role in abiotic stress responses, but molecular modes that enable this activity remain largely unknown. Here we show that BRs participate in the regulation of freezing tolerance. BR signaling-defective mutants of Arabidopsis thaliana were hypersensitive to freezing before and after cold acclimation. The constitutive activation of BR signaling, in contrast, enhanced freezing resistance. Evidence is provided that the BR-controlled basic helix–loop–helix transcription factor CESTA (CES) can contribute to the constitutive expression of the C-REPEAT/DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR (CBF) transcriptional regulators that control cold responsive (COR) gene expression. In addition, CBF-independent classes of BR-regulated COR genes are identified that are regulated in a BR- and CES-dependent manner during cold acclimation. A model is presented in which BRs govern different cold-responsive transcriptional cascades through the posttranslational modification of CES and redundantly acting factors. This contributes to the basal resistance against freezing stress, but also to the further improvement of this resistance through cold acclimation.

Nitric oxide as a signaling molecule in brassinosteroid‐mediated virus resistance to Cucumber mosaic virus in Arabidopsis thaliana

“…Brassinosteroids (BRs) are a widespread group of plant hormones that play a crucial role during plant growth and development (Wang et al ). Furthermore, BRs play a role in abiotic stress responses, such as drought, low temperature, freezing tolerance and heavy metal contamination (Kagale et al , Fowler and Thomashow , Eremina et al , Rajewska et al ). Several recent studies also revealed that BRs participate in pathogen defense responses (Heese et al , Albrecht et al , Belkhadir et al , Wang ), and brassinolide (BL) could induce disease resistance both in tobacco and rice (Nakashita et al ).…”

Insights into the regulation of C‐repeat binding factors in plant cold signaling

“…To date, several transcriptional regulators of the CBF s have been identified, including ICE1/2 (Inducer of CBF expression), MYB15, CAMTA3 (Calmodulin‐binding transcription activator 3), EIN3 (Ethylene insensitive 3), SOC1 (Suppressor of overexpression of co 1), PIF3/4/7 (Phytochrome‐interacting factors), CCA1 (Circadian clock associated 1), LHY (Late elongated hypocotyl), BZR1 (Brassinazole‐resistant 1)/BES1 (BRI1‐EMS suppressor 1), and CESTA (Chinnusamy et al ; Agarwal et al ; Doherty et al ; Fursova et al ; Seo et al ; Dong et al ; Lee and Thomashow ; Shi et al ; Eremina et al ; Jiang et al ; Li et al ) (Figure ).…”

“…The components of BR (brassinosteroid) signaling are reported to positively regulate the cold‐induced transcription of the CBF s (Eremina et al ; Li et al ). BZR1, BES1, and CES (CESTA) are the key positive regulators of the BR response (He et al ; Yin et al ), and recent studies revealed that these transcription factors directly bind to the E‐box and BRRE binding sites of the CBF1 and CBF2 promoters, positively regulating their expression (Eremina et al ; Li et al ).…”

“…The gain‐of‐function BZR1, BES1 and CES mutants in Arabidopsis had significantly enhanced freezing tolerances, whereas the ces‐2 bee1 bee2 bee3 quadruple mutant was hypersensitive to freezing (Eremina et al ). Biochemical evidence indicated that cold treatment induced the accumulation of non‐phosphorylated BZR1 protein in plants (Li et al ).…”

“…RNA‐seq analysis revealed that BZR1 and CES also regulate CBF ‐independent gene expression to regulate plant freezing tolerance (Eremina et al ; Li et al ). These results indicate that some components in BR signaling are involved in regulating cold stress response in both CBF‐dependent and CBF‐independent manners.…”