The dynamic regulation response to salt stress in poplar

Key message

This study focuses on poplar root's dynamic salt stress responses, finding that Hsp20s may play an important role and screening its upstream regulators.

Abstract

Populus davidiana × P. alba, an excellent tree species, which is widely planted in China, has been seriously affected by salt stress. In this study, the response of poplar roots to salt stress was deeply studied by time-course transcriptome, and a large number of differentially expressed genes (DEGs) were identified at different times. Through weighted gene co-expression network analysis (WGCNA), it was discovered that oxidative and osmotic stress regulation played a crucial role in resisting salt stress in the early salt stress response (3–6 h), and nitrogen metabolize and transport genes were identified as hub genes. At the middle stage of salt stress (12–24 h), the plants initiated extensive reprogramming to adapt to stress, and the transcription factors (TFs), WRKY53, MYB13 and NFXL1, were identified as hub genes. After 48 h of salt stress, seven PdaHsp20 genes were identified as hub genes, which may alleviate the damage of salt stress. The genome-wide analysis of Hsp20s showed that the Hsp20 proteins were divided into 11 groups. A three-layer gene regulatory network with PdaHsp20s as the underlying gene was constructed and the unique PdaERF72 was found by association analysis with the co-expression network, which may have important functions in regulating PdaHsp20s under salt stress. The expression level analysis of PdaERF72 and PdaHsp20s, which have a direct connection with it, also indicated that some of them may have a negative regulation relationship after salt stress. In a word, poplar dynamically responds to salt stress, and different hub genes play a role in different stress stages, which provided a new perspective to reveal the response mechanism of poplar to salt stress.