The pH Modulation by Fungal Secreted pH Effecting Molecules: A Mechanism Affecting Pathogenicity and Mycotoxin Accumulation During Colonization by Penicillium expansum
Dov Prusky, Shiri Barad, Nofar Glam, Nancy Keller and Amir Sherman
from: Aspergillus and Penicillium in the Post-genomic Era (Edited by: Ronald P. de Vries, Isabelle Benoit Gelber and Mikael Rørdam Andersen). Caister Academic Press, U.K. (2016) Pages: 173-188.
A postharvest pathogen as Penicillium can start its attack process as soon as spores land on wounded tissue; other pathogens as Colletotrichum breach the unripe fruit cuticle, remain quiescent for months until the fruit ripens and then colonize the host. Both post-harvest fungal pathogens initiate their development by secreting non-proteinaceous pH modulating factors as organic acids or ammonia, which acidify or alkalinize the ambient host environment. These fungal secreted pH effecting molecules (SEM) modulate the host environment, activate secondary metabolism and regulate an arsenal of enzymes in order to increase fungal pathogenicity under any specific conditions. This arsenal includes genes and processes that compromise host defenses, enhance programmed cell death (PCD), contribute to intracellular signaling, produce cell-wall-degrading enzymes, regulate specific transporters, induce redox protectant systems and generate factors needed by the pathogen to cope effectively with the hostile environment found within the host. In Penicillium, genes that contribute to gluconic acid (GLA) and secondary metabolites accumulation found to be pH regulated by the specific transcription factor PacC, indicating the capability to respond under acidifying modes of attack. In this chapter we will analyze Penicillium capability to modulate the environment pH as a mechanism for colonization read more ...