Overexpression of TaMYC2 confers freeze tolerance by ICE-CBF-COR module in Arabidopsis thaliana

Abstract

Dongnongdongmai No.1 (Dn1) is one of the few winter wheat varieties that can successfully overwinter at temperatures as low as -25°C or even lower. To date, few researches were carried to identify the freeze tolerance genes in Dn1 and applied them to improve plant resistance to extreme low temperatures. The basic helix-loop-helix (bHLH) transcription factor MYC2 is a master regulator in JA signaling, which has been reported to involve in responses to mild cold stress (2°C and 7°C). We hypothesized that MYC2 might be part of the regulatory network responsible for the tolerance of Dn1 to extreme freezing temperatures. In this study, we showed that wheat MYC2 (TaMYC2) was induced under both extreme low temperature (-10°C and-25°C) and JA treatments. The ICE-CBF-COR transcriptional cascade, an evolutionary conserved cold resistance pathway downstream of MYC2, was also activated in extreme low temperatures. We further showed that overexpression of any of the MYC2 genes from Dn1 TaMYC2A, B, D in Arabidopsis led to enhanced freeze tolerance. The TaMYC2 overexpression lines had less electrolyte leakage and lower malondialdehyde (MDA) content, and an increase in proline content, an increases antioxidant defences, and the enhanced expression of ICE-CBF-COR module under the freezing temperature. We further verified that TaMYC2 might function through physical interaction with TaICE41 and TaJAZ7, and that TaJAZ7 physically interacts with TaICE41. These results elucidate the molecular mechanism by which TaMYC2 regulates cold tolerance and lay the foundation for future studies to improve cold tolerance in plants.

Overexpression of TaMYB4 Confers Freezing Tolerance in Arabidopsis thaliana

“…The MDA content and EC determination method was carried out in accordance with a previous study [ 47 ]. Pro content was determined using a kit (Comin).…”

Functions of Basic Helix–Loop–Helix (bHLH) Proteins in the Regulation of Plant Responses to Cold, Drought, Salt, and Iron Deficiency: A Comprehensive Review

“…For example, PtrICE1 modulates the levels of polyamines by interacting with ARGININE DECARBOXYLASE (PtADC), resulting in increased cold stress tolerance in transgenic lemons. − Cheng first reported that Arachis hypogaea AnICE1 might regulate the expression of AnCBF2 , thereby enhancing the cold stress resistance of transgenic Arabidopsis . Another study revealed the interaction between the K domains of ANTIFREEZE PROTEIN (AnAFP) and AnICE1. , HbJAZ1/12 proteins interact with HbICE2 to attenuate the transcriptional function of HbICE2, subsequently inhibiting the expression of downstream genes in rubber tree. , The same research group also discovered EcaSIZ1 and EcaHOS1, which interact with EcaICE1 in enhancing cold tolerance. , Other research groups reported that TaMYC2D forms a ternary complex with TaICE41 and TaJAZ7 thus regulating freeze tolerance . Overall, further studies are needed to better understand the functional significance of bHLH protein dimerization in enhancing the cold tolerance in plants.…”

Responses of sorghum to cold stress: A review focused on molecular breeding

“…The mechanism of growth inhibition also involves the stimulation of gibberellin-inactivating enzymes in a process that promotes survival or escape from adverse environmental conditions (Achard et al, 2008). The reduction in growth could also be caused by an increase in reactive oxygen species (ROS) in plants, which affects growth and reduces crop yield (Devireddy et al, 2021;Wang et al, 2022).…”

“…They determine whether a specific gene will be turned "on" or "off" (Philips and Hoopes, 2008). Currently, the plant's most understood cold-signaling pathway is the CBF/DREB transcriptional regulatory cascade (Shi et al, 2015;Wang et al, 2022). The CBF genes respond rapidly to chilling temperatures and induce the expression of several proteins that protect plants from freezing temperatures.…”

“…Sorghum genes that are predicted to be involved in ethylene biosynthesis, which regulates cold signaling pathways, were upregulated (Marla et al, 2017). Recently, it was indicated that TaMYC2 plays a critical role in cold stress in many plants and activates the ICE (inducer of CBF expression)-CBF-COR (cold responsive) cold resistance pathway through interaction with ICE in Arabidopsis (Wang et al, 2022), and some MYC2 (A/B/D) improved cold tolerance through ROS metabolic.…”