Apoplastic hydrophobic proteins involved in tuber defense response to P. Infestans
During infection, oomycetes secrete effectors into the plant apoplast where they interact with host resistance proteins. In response, large amounts of protease and protease inhibitors (PIs), are accumulated. We analyzed differentially expressed Apoplastic Hydrophobic Proteins (AHPs) in potato tubers from Innovator (resistant) and Spunta (susceptible) cvs, after wounding and P. infestans infection. Intercellular washing fluid was extracted from control, wounded or infected tubers at 0, 24 and 48 h and chromatographed into a PepRPCtmHR5/5 in FPLC. After elution with acetonitrile, fractions were analyzed by SDS-PAGE and proteins identified by MALDITOF- MS. Innovator cv. showed a higher basal AHP content and hydrophobicity than Spunta cv. In the latter, infection induced accumulation of patatins and PIs, whereas in Innovator cv. no changes in PIs accumulation were observed. In response to P. infestans infection, lypoxigenase, enolase, annexin p34 and glutarredoxin/cyclophilin were accumulated in both cvs. Hydrophobicity of AHPs was higher after 24 h of wounding and infection in both cultivars. These results suggest that an increase in AHPs concentration would be related with the protection against the oomycete and with the degree of resistance to pathogens. Finally, changes in hydrophobicity of Pis may induce changes in proteaseinhibitor interaction affecting the defense response.