A modified Rpl3 gene from rice confers tolerance of the Fusarium graminearum mycotoxin deoxynivalenol to transgenic tobacco

The mycotoxin deoxynivalenol (DON) produced by Fusarium graminearum is a potent inhibitor of eukaryotic protein synthesis and is believed to play a role in fungal pathogenesis on cereal crops worldwide. The putative site of action of this molecule has been theorized to be the 60S ribosomal protein L3 (RPLS). We have modified a rice (Oryza saliva L.) cDNA encoding the ribosomal protein RPL3 so that amino acid residue 258 is changed from tryptophan to cysteine. a change which is believed to confer resistance to similar mycotoxins in yeast. Both versions of the rice Rpl3 genes were introduced into two species of tobacco by Agrobacterium tumefaciens co-cultivation and expressed under the control of a constitutive promoter. When cells, tissues, and protoplasts of these transgenic tobacco plants were compared for growth in the presence of DON, a significant difference in growth rate and the ability to undergo differentiation was observed among those plants expressing the modified version of the Rpl3 gene (Rpl3:c258), compared to those expressing the wild-type Rpl3 gene. These results indicate a possible mechanism of host plant resistance to the fungal pathogen F. graminearum among the susceptible cereal species based on the expression of modified Rpl3 genes.