摘要Salinity severely reduces plant growth and limits agricultural productivity.Dynamic changes and rear-rangement of the plant cell wall is an important response to salt stress,but relatively little is known about the biological importance of specific cell wall components in the response.Here,we demonstrate a specific function of β-1,4-galactan in salt hypersensitivity.We found that salt stress induces the accumulation of β-1,4-galactan in root cell walls by up regulating the expression of GALACTANSYNTHASE1(GALS1),which encodes a β-1,4-galactan synthase.The accumulation of β-1,4-galactan negatively affects salt tolerance.Exogenous application of D-galactose(D-Gal)causes an increase in β-1,4-galactan levels in the wild type and GALS1 mutants,especially in GALS1 overexpressors,which correlated with the aggravated salt hyper-sensitivity.Furthermore,we discovered that the BARLEY B RECOMBINANT/BASIC PENTACYSTEINE tran-scription factors BPC1/BPC2 positively regulate plant salt tolerance by repressing GALS1 expression and β-1,4-galactan accumulation.Genetic analysis suggested that GALS1 is genetically epistatic to BPC1/BPC2 with respect to the control of salt sensitivity as well as accumulation of β-1,4-galactan.Taken together,our results reveal a new regulatory mechanism by which β-1,4-galactan regulated by the BPC1/BPC2-GALS1 module aggravates salt sensitivity in Arabidopsis thaliana.