The Differential Growth Inhibition of Phytophthora spp. Caused by the Rare Sugar Tagatose Is Associated With Species-Specific Metabolic and Transcriptional Changes

Abdessalem Chahed, Valentina Lazazzara, Marco Moretto, Andrea Nesler, Paola Elisa Corneo, Essaid Ait Barka, Ilaria Pertot, Gerardo Puopolo and Michele Perazzolli

INFORMATIVE ABSTRACT - Rare sugars are monosaccharides with a scarce presence in nature known for their role as contrast agent of plant diseases, contributing to plant growth and immune responses against pests and pathogens. Tagatose is one of the rare sugars used also as artificial sweetener. One of the characteristics of tagatose is its ability to inhibit a large spectrum of phytopathogens. In particular tagatose inhibits Phytophthora infestans growth (P. infestans is a mold responsible of a disease on potatoes and tomatoes) and negatively affects mitochondrial processes. However, this phenomenon doesn’t happen in Phytophtora cinnamomi.

P. infestans and P. cinnamomi in fact activate distinct metabolic changes and transcriptional reprograms in response to tagatose, and this study wants to clarify the differential inhibitory mechanisms of tagatose and the species-specific reactions to it.
In P. infestans, tagatose negatively affects mycelial growth, sugar content and amino acid content through a severe transcriptional reprogramming that includes the downregulation of genes involved in transport, sugar metabolism, signal transduction, and growth-related process. But tagatose doesn’t have this effect in P. Cinnamomi, in which it happens a upregulation of genes related to transport, energy metabolism, sugar metabolism and oxidative stress. The researchers found that this different answer to the inhibition ability of tagatose is due to a stronger ability of P. Cinnamomi to resist him, reprogramming multiple metabolic processes.