Interactions of tagatose with the sugar metabolism are responsible for Phytophthora infestans growth inhibition

Paola Elisa Corneo, Andrea Nesler, Cesare Lotti, Abdessalem Chahed, Urska Vrhovsek, Ilaria Pertot, Michele Perazzolli

INFORMATIVE ABSTRACT - Tagatose is a rare sugar metabolised by a limited number of microorganisms and it can be produced by lactose when milk is heated and is used as an artificial sweetener (indeed he is recognized as safe by the WHO and FAO). One of the characteristics of tagatose is his ability to inhibit a large spectrum of phytopathogens, and in particular it inhibits Phytophthora infestans (P. infestans is a water mold that causes a disease on potatoes and tomatoes) growth and negatively affects mitochondrial processes. In the study was analysed the effects that tagatose produce on the sugar metabolism in P. infestans. The inhibition of the growth of P. infestans takes place through a precise reprogramming of the carbohydrate metabolism that involved a decrease of glucose, glucose-1-phosphate and mannose content and β-glucosidase activity. The experiments show how the combination of tagatose with common sugars lead to three different responses and highlight antagonistic interactions:
• glucose partially attenuates the inhibitory effects of tagatose;
• fructose fully impair tagatose-mediated growth inhibition and metabolite changes;
• sucrose didn’t attenuate tagatose effects.

The results suggest that the inhibition of sucrose catabolism and the alteration of glucose-related pathways contribute to the growth inhibition caused by tagatose to P. infestans, finding that these interactions with sugar metabolism lead to stop P. infestans growth. On the other side, this study provides useful information about the interference of Tagatose’s efficacy with fructose and likely with other common sugars.
In this way the research could be the basis for other studies with the purpose of developing tagatose as an eco-friendly fungicide.