Temperature is an essential environmental factor affecting plant growth and development, as well as resistance against pathogens. Low temperature promotes plant immune responses, and this process may involve the salicylic acid (SA) signaling pathway in plants. However, the underlying mechanism by which low temperature signals coordinate SA signaling to regulate plant immunity responses is not fully understood.
In a study published in The Plant Cell, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) revealed the molecular mechanism of low temperature-enhanced plant immune response. They demonstrated a critical function of the INDUCER OF CBF EXPRESSION 1 (ICE1) as an essential node bridging cold stimulus and plant immunity.
To investigate the underlying relationship between low temperature and plant immunity, the researchers assessed effect of low temperature on plant immune responses against the hemibiotropic pathogenic bacteria, Pseudomonas syringae pv. tomato (Pst) DC3000.
Mechanistic analyses revealed that the ICE1 protein physically interacts with the salicylic acid (SA) receptor NON-EXPRESSER OF PR GENES 1 (NPR1) and is involved in SA-mediated resistance against Pst DC3000. The ice1-2 mutant exhibited enhanced susceptibility to pathogen infection, including severe pathogen-related water soaking symptoms and high pathogen proliferation, and decreased expression of PATHOGENESIS-RELATED GENE 1 (PR1).
Most importantly, they found that ICE1 was a key regulatory node of low-temperature and salicylic acid signals, because the coordinated function of cold- and SA- enhanced immunity was diminished in ice1-2 mutant plants. They also found that ICE1 interacted with TGACG-BINDING FACTORs (TGA) transcription factors to cooperatively stimulate PR1 expression under low temperatures.
"Therefore, the major underlying mechanism is that ICE1 activates the expression of PR1 and this activation is promoted by NPR1,” said LI Shaoqin, first author of the study.
"Our findings not only provide evidence that ICE1 is an essential component of SA signal pathway at low temperature, but also increase our understanding of the role of the NPR1-ICE1-TGA3 regulatory module in integrating low temperature signal in activating plant immunity,” said JIANG Yanjuan, a former researcher of XTBG.
Contact
JIANG Yanjuan Ph.D
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail: jiangyj@xtbg.ac.cn
First published: 27 March 2024
