ICE1, short for INDUCER OF C-REPEAT BINDING FACTOR (CBF) EXPRESSION1, is a crucial transcriptional regulator. It is a key component in the cold-signal cascades, playing a significant role in plant cold stress responses by regulating the expression of CBF genes, which in turn activate downstream cold-responsive (COR) genes essential for freezing tolerance [1,2,3,4,8]. Additionally, ICE1 is involved in other biological processes such as seed dormancy, pollen development, and plant immunity [5,6,7].

In Arabidopsis, studies have shown that various factors modulate ICE1 stability and activity. For example, PUB25 and PUB26, two PLANT U-BOX E3 ligases, facilitate both K48-and K63-linked ubiquitination of ICE1 during different periods of cold stress, dynamically modulating its stability [1]. MPK3 and MPK6 phosphorylate ICE1, reducing its stability and transcriptional activity, while OST1 phosphorylates ICE1 to enhance its stability and transcriptional activity, and interferes with HOS1-mediated ICE1 degradation [3,4]. Also, MYB43 interacts and antagonizes with ICE1 to regulate the expression of CBF genes and plant's freezing stress tolerance [8]. In tomato, CaM6 interacts with ICE1 in a Ca2 +-independent process and attenuates its transcriptional activity during cold stress [2].

In conclusion, ICE1 is a vital regulator in plants, playing key roles in cold stress responses, seed dormancy, pollen development, and immunity. Studies on ICE1, especially through genetic models like those in Arabidopsis, have provided insights into its complex regulatory mechanisms. Understanding these mechanisms can potentially contribute to improving plant tolerance to cold stress and other related agricultural challenges.

References:

1. Wang, Xi, Zhang, Xiaoyan, Song, Chun-Peng, Yang, Shuhua, Ding, Yanglin. . PUB25 and PUB26 dynamically modulate ICE1 stability via differential ubiquitination during cold stress in Arabidopsis. In The Plant cell, 35, 3585-3603. doi:10.1093/plcell/koad159. https://pubmed.ncbi.nlm.nih.gov/37279565/

2. Lin, Rui, Song, Jianing, Tang, Mingjia, Yu, Jingquan, Zhou, Yanhong. . CALMODULIN6 negatively regulates cold tolerance by attenuating ICE1-dependent stress responses in tomato. In Plant physiology, 193, 2105-2121. doi:10.1093/plphys/kiad452. https://pubmed.ncbi.nlm.nih.gov/37565524/

3. Li, Hui, Ding, Yanglin, Shi, Yiting, Gong, Zhizhong, Yang, Shuhua. 2017. MPK3- and MPK6-Mediated ICE1 Phosphorylation Negatively Regulates ICE1 Stability and Freezing Tolerance in Arabidopsis. In Developmental cell, 43, 630-642.e4. doi:10.1016/j.devcel.2017.09.025. https://pubmed.ncbi.nlm.nih.gov/29056553/

4. Ding, Yanglin, Li, Hui, Zhang, Xiaoyan, Gong, Zhizhong, Yang, Shuhua. . OST1 kinase modulates freezing tolerance by enhancing ICE1 stability in Arabidopsis. In Developmental cell, 32, 278-89. doi:10.1016/j.devcel.2014.12.023. https://pubmed.ncbi.nlm.nih.gov/25669882/

5. Li, Shaoqin, He, Li, Yang, Yongping, Hu, Yanru, Jiang, Yanjuan. . INDUCER OF CBF EXPRESSION 1 promotes cold-enhanced immunity by directly activating salicylic acid signaling. In The Plant cell, 36, 2587-2606. doi:10.1093/plcell/koae096. https://pubmed.ncbi.nlm.nih.gov/38536743/

6. MacGregor, Dana R, Zhang, Naichao, Iwasaki, Mayumi, Lopez-Molina, Luis, Penfield, Steven. 2019. ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development. In The Plant journal : for cell and molecular biology, 98, 277-290. doi:10.1111/tpj.14211. https://pubmed.ncbi.nlm.nih.gov/30570804/

7. Luo, Landi, Zheng, Yan, Li, Xieshengyang, Kong, Xiangxiang, Yang, Yongping. 2024. ICE1 interacts with IDD14 to transcriptionally activate QQS to increase pollen germination and viability. In Journal of integrative plant biology, 66, 1801-1819. doi:10.1111/jipb.13725. https://pubmed.ncbi.nlm.nih.gov/38940322/

8. Zheng, Pengpeng, Cao, Lei, Zhang, Cheng, Liu, Yongsheng, Cao, Shuqing. 2023. The transcription factor MYB43 antagonizes with ICE1 to regulate freezing tolerance in Arabidopsis. In The New phytologist, 238, 2440-2459. doi:10.1111/nph.18882. https://pubmed.ncbi.nlm.nih.gov/36922399/