Rare Sugars: Recent Advances and Their Potential Role in Sustainable Crop Protection

Abstract

Rare sugars are monosaccharides with a limited availability in the nature and almost unknown biological functions. The use of industrial enzymatic and microbial processes greatly reduced their production costs, making research on these molecules more accessible. Since then, the number of studies on their medical/clinical applications grew and rare sugars emerged as potential candidates to replace conventional sugars in human nutrition thanks to their beneficial health effects. More recently, the potential use of rare sugars in agriculture was also highlighted. However, overviews and critical evaluations on this topic are missing. This review aims to provide the current knowledge about the effects of rare sugars on the organisms of the farming ecosystem, with an emphasis on their mode of action and practical use as an innovative tool for sustainable agriculture. Some rare sugars can impact the plant growth and immune responses by affecting metabolic homeostasis and the hormonal signaling pathways. These properties could be used for the development of new herbicides, plant growth regulators and resistance inducers. Other rare sugars also showed antinutritional properties on some phytopathogens and biocidal activity against some plant pests, highlighting their promising potential for the development of new sustainable pesticides. Their low risk for human health also makes them safe and ecofriendly alternatives to agrochemicals.

D-Tagatose-Based Product Triggers Sweet Immunity and Resistance of Grapevine to Downy Mildew, but Not to Gray Mold Disease

“…In recent years, some rare monosaccharides and their derivatives have shown potential functional and ecological properties in controlling plant pathogens [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Their availability has been achieved through the implementation of new enzymatic and microbial processes, making their use effective in food and agricultural sectors [ 25 , 30 ]. D-tagatose, as a ketohexose, is among rare sugars found at low concentrations in many foods and generally recognized as safe by the Food and Drug Administration [ 30 ].…”

A review of knowledge on the mechanisms of action of the rare sugard‐tagatose against phytopathogenic oomycetes

“…Fisher projections and inhibitory properties against Phytophthora infestans are reported for some rare sugars with structural similarities with dfructose and potential applicative value. According to the protocol reported by Chahed et al (2020), P. infestans growth was inhibited (p ≤ 0.05; Kruskal-Wallis test) by 5 g/L d-tagatose (84.20 ± 0.23%; mean inhibition percentage and standard error compared to control samples) and 5 g/L l-sorbose (42.04 ± 0.12% this study), but it was not affected by 5 g/L d-psicose (0.22 ± 0.13%), 5 g/L d-sorbose (0.39 ± 0.15%), and 5 g/L d-fructose (0.19 ± 0.11%) some phytopathogens and it has been proposed as a promising plant protection product (Chahed et al, 2020(Chahed et al, , 2021Corneo et al, 2021b;Mijailovic et al, 2021;Mochizuki et al, 2020;Perazzolli et al, 2020).…”

“…Rare sugars comprise 20 hexoses (d-allose, l-allose, d-altrose, l-altrose, l-fructose, l-galactose, (Ahmed, 2001;Izumori et al, 2008;Jayamuthunagai et al, 2017). The biological properties of rare sugars are not fully understood and their promising applicative values are underestimated, mainly because of their limited available quantity in nature (Li et al, 2013;Mijailovic et al, 2021). However, the development of innovative enzymatic and microbial methods for rare sugar synthesis have lowered the cost of production and expanded their application in several scientific and technological areas of medicine, food, and agriculture (Granström et al, 2004;Li et al, 2013;Oh, 2007).…”

Naturally occurring non-nutritive sweeteners: A review

“…D-allulose has shown hypoglycemic, improved insulin resistance, hypolipidemic and obesity properties. It has antiinflammatory, anti-artherosclerotic properties and serves as a neuroprotectant (Mijailovic, N, 2021) [51] . The exceptional physiochemical properties make it a viable substitute for Dsucrose in foods.…”