In general, cell wall-degrading
enzymes produced by plant pathogenic fungi are considered important
pathogenicity factors. In this work, we evaluate the implication of
xyloglucan endotransglucosylase/hydrolase (XTHs), a potential hemicellulosic repairing
enzyme, in the
infection mechanism process by the fungus. This study investigated the SlXTHs expresion and
xyloglucan endotransglucosylase (XET) activity during
infection of two tomato fruit cultivars by Penicillium expansum Link. A. In infected fruits, XET specific activity decreased drastically after long
infection periods, 24 and 48 h for Canario and Money Maker tomato fruits, respectively. Real Time RT-PCR of eleven SlXTHs also showed a decrease in expression as the
infection progressed in both tomato fruit cultivars. Results suggest that the reduction in SlXTHs expression during
infection might be related with the fungus attack mechanism. We suggest a possible transcriptional control of the SlXTHs expression by the fungus, causing a decrease in XET activity and, consequently, lower
xyloglucan endotransglucosylation, which changes the
xyloglucan structure. These changes might increase the fruit softening and wall disassembly, facilitating the fungus colonization and the progress of the
infection.