IDENTIFICATION OF SEPTORIA TRITICI CONIDIOSPORES PROTEINS DEGRADED BY WHEAT LEAF APOPLAST PROTEASES

MANSILLA, A.; RONCHI, V.; CONDE, R.; SEGARRA, C.

Rosario - Santa Fe - Argentina

Congreso; XLII Reunion Annual SAIB (Sociedad Argentina de Investigación en Bioquímica y Biología Molecular); 2006

SAIB

We have previously described a wheat leaf intercellular fluid serine protease that blocks Septoria tritici conidiospore  germination. Thus, it controls the wheat leaf blotch caused by S. tritici in resistant cultivars. Based on these results, the identity of  S. tritici spore proteins degraded by the intercellular fluid serine protease was explored. For it, 2D SDS-PAGE patterns of spore  protein extracts incubated with the intercellular fluid at 37 °C for 3 hours were analyzed. Degradation of several spore proteins was detected. The identity of these proteins, as well of other nondegraded, was examined by HPLC - Mass spectrometry followed by alignment of sequences in databases. Results suggest that main protease substrate is 2-oxoglutarate  dehydrogenase. It comprises multiple copies of three enzymes which are analogues of those of pyruvate dehydrogenase.  Conversely, aldehyde dehydrogenase plus a still nonidentified spot were main stable proteins. Corroboration of these  identifications and the posterior analysis of other proteins separated by 2D SDS-PAGE will allow advancing significantly in  understanding the defense of wheat against S. tritici.