Overexpression of FBR 41 enhances resistance to sphinganine analog mycotoxin‐induced cell death and Alternaria stem canker in tomato

Fumonisin B1 ( FB 1) and Alternaria alternate f. sp. lycopersici ( AAL )‐toxin are classified as sphinganine analog mycotoxins ( SAMT s), which induce programmed cell death ( PCD ) in plants and pose health threat to humans who consume the contaminated crop products. Herein, Fumonisin B1 Resistant41 ( FBR 41 ), a dominant mutant allele, was identified by map‐based cloning of Arabidopsis FB 1‐resistant mutant fbr41 , then ectopically expressed in AAL ‐toxin sensitive tomato ( Solanum lycopersicum ) cultivar. FBR 41 ‐overexpressing tomato plants exhibited less severe cell death phenotype upon AAL ‐toxin treatment. Analysis of free sphingoid bases showed that both fbr41 and FBR 41 ‐overexpressing tomato plants accumulated less sphinganine and phytosphingosine upon FB 1 and AAL ‐toxin treatment, respectively. Alternaria stem canker is a disease caused by AAL and responsible for severe economic losses in tomato production, and FBR 41 ‐overexpressing tomato plants exhibited enhanced resistance to AAL with decreased fungal biomass and less cell death, which was accompanied by attenuated accumulation of free sphingoid bases and jasmonate ( JA ). Taken together, our results indicate that FBR 41 is potential in inhibiting SAMT ‐induced PCD and controlling Alternaria stem canker in tomato.