The study examined early metabolic responses to salt stress in a salt‑tolerant alfalfa cultivar, focusing on SnRK1 activity, sucrose, and trehalose‑6‑phosphate dynamics during leaf expansion. Hydroponically grown plants exposed to 200 mM NaCl showed rapid, wave‑like SnRK1 activation within 1 hour, a transient decline in chloroplast performance, and an uncoupling of the Tre6P‑sucrose regulatory link, with a second SnRK1 peak correlating with reduced leaf growth. Exogenous sucrose inhibited SnRK1 activity, highlighting early SnRK1 activation as a pivotal component of salt stress adaptation.

The study shows that silencing of NOR2 rRNA genes in Arabidopsis thaliana depends primarily on CHH-context cytosine methylation, particularly mediated by CMT2 and the chromatin remodeler DDM1, rather than CG or CHG methylation. Comparative promoter analysis revealed a prevalence of CHH sites in plant rDNA promoters, explaining why CHH methylation mutants disrupt NOR2 silencing more strongly, while NOR2 loci are hyper‑methylated and more condensed than NOR4.