Subcellular localization of rice acyl‐CoA‐binding proteins (ACBPs) indicates that OsACBP6::GFP is targeted to the peroxisomes

Summary Acyl‐CoA‐binding proteins ( ACBP s) show conservation at the acyl‐CoA‐binding ( ACB ) domain which facilitates binding to acyl‐CoA esters. In Arabidopsis thaliana , six ACBP s participate in development and stress responses. Rice ( Oryza sativa ) also contains six genes encoding ACBP s. We investigated differences in subcellular localization between monocot rice and eudicot A. thaliana ACBP s. The subcellular localization of the six Os ACBP s was achieved via transient expression of green fluorescence protein ( GFP ) fusions in tobacco ( Nicotiana tabacum ) epidermal cells, and stable transformation of A. thaliana . As plant ACBP s had not been reported in the peroxisomes, Os ACBP 6:: GFP localization was confirmed by transient expression in rice sheath cells. The function of Os ACBP 6 was investigated by overexpressing 35S::OsACBP6 in the peroxisomal abc transporter1 ( pxa1 ) mutant defective in peroxisomal fatty acid β‐oxidation. As predicted, Os ACBP 1:: GFP and Os ACBP 2:: GFP were localized to the cytosol, and Os ACBP 4:: GFP and Os ACBP 5:: GFP to the endoplasmic reticulum ( ER ). However, Os ACBP 3:: GFP displayed subcellular multi‐localization while Os ACBP 6:: GFP was localized to the peroxisomes. 35S::OsACBP6‐OE/pxa1 lines showed recovery in indole‐3‐butyric acid ( IBA ) peroxisomal β‐oxidation, wound‐induced VEGETATIVE STORAGE PROTEIN1 ( VSP1 ) expression and jasmonic acid ( JA ) accumulation. These findings indicate a role for Os ACBP 6 in peroxisomal β‐oxidation, and suggest that rice ACBP s are involved in lipid degradation in addition to lipid biosynthesis.