Plants have constitutive resistance to infection by several fungi due to the presence of saponins (glycosylated steroidal or triterpenoid compounds) in the cells. Several fungi have developed a way to overcome this resistance by expressing an enzyme able to break down the corresponding saponin.
Avenacin A1 and oc-tomatin are two saponins which can be hydrolysed by the enzymes avenacinase and tomatinase, respectively, which are produced by plant pathogenic fungi. Using a phage displaying antibodies library, I will isolate antibodies against these two enzymes able to block their action. I will use the genes encoding these antibodies to transform oat and tomato embryogenic cells to produce transgenic plants resistant to their infecting fungi that can also be used to study more precisely the mechanisms of resistance. To improve the understanding of these mechanisms, I will also generate antibodies against oc-tomatine that can serve for the screening of mutant plants after mutagenesis to obtain tomatin-deficient mutants.