β-1,4-galactan is one of the major cell wall polysaccharides and generally found as a side chain of rhamnogalacturonan I. A few studies have shown that β-1,4-galactan play a role in plant growth and development. However, Arabidopsis mutants essentially devoid of β-1,4-galactan show surprisingly normal growth and development , suggesting that the important function of this polysaccharide would be more obvious under specific growth conditions, e.g. abiotic stress conditions. Here, we demonstrated a specific function of β-1,4-galactan in salt hypersensitivity.