Lysine acetylome analysis reveals the critical role of acetylation-modified transcription factors and a chaperone protein in regulation of salt tolerance in Tamarix hispida.

Background

Lysine acetylation of transcription factors (TFs) is essential for plant adaptation to abiotic stress, yet its role in the salt tolerance of woody halophytes remains unclear.

Results

Using 4D label-free quantitative acetylproteomics, we profiled the lysine acetylome of Tamarix hispida under 200 mM NaCl stress. We identified 7,557 lysine acetylation (Kac) sites on 3,136 proteins, of which 559 sites on 478 proteins were salt-responsive. KEGG enrichment analysis revealed that these proteins were primarily involved in pyruvate metabolism and carotenoid biosynthesis, suggesting that acetylation remodels central metabolic pathways during salt adaptation. Salt stress also increased acetylation of five histones and two histone acetyltransferases (KAT3 and NAT3), implicating epigenetic mechanisms. Among 24 acetylated proteins from six families of TFs and one non-TF target protein (HSP), HSPs and zinc-finger types were predominant. Mutation of Kac sites in four selected proteins (ThNAC68, ThCHCC, ThC3H, ThHSP70) abolished their salt-induced acetylation. Transient overexpression of wild-type versions enhanced salt tolerance, lowering malondialdehyde (MDA) and reactive oxygen species (ROS) while elevating proline, chlorophyll, and antioxidant enzyme activities; these effects were lost in acetylation-defective mutants.

Conclusions

Our work delineates the lysine acetylome of T. hispida under salt stress and establishes TF acetylation as a key regulatory layer in salt adaptation, offering new insights into post-translational and epigenetic networks underlying stress tolerance in woody plants.