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

Abstract

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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

“…Rare sugars have been shown to reduce severity of various plant diseases and their effectiveness depends on the pathogen lifestyle [ 25 , 28 , 29 , 30 , 31 ]. For instance, D-tagatose was more effective against biotroph oomycetes including grapevine downy mildew, than necrotrophs like B. cinerea [ 31 , 32 , 33 , 34 ].…”

“…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 ].…”

“…It is also likely that a coordinated interaction of sugar and hormonal pathways in plants leads to effective induction of defense responses [ 15 ]. Although the effectiveness of tagatose against some fungal and oomycete pathogens was reported [ 25 , 26 , 31 , 35 ], the molecular mechanisms involved in grapevine protection against downy mildew and gray mold remained to be elucidated.…”

The Amount of the Rare Sugar Tagatose on Tomato Leaves Decreases after Spray Application under Greenhouse Conditions

“…Tagatose is known to suppress late blight symptoms on tomato plants under greenhouse conditions [ 14 , 15 ] and to inhibit P. infestans growth in vitro [ 8 , 9 , 10 , 12 ]. A negligible amount of tagatose was found on H 2 O-treated plants in our experiments, and it was also previously detected on untreated cucumber leaves [ 11 ] and grapevine leaves [ 17 ], as well as in apples, pineapples, oranges, and raisins [ 5 ], suggesting that a small tagatose quantity could be produced by plant and/or microbial metabolism.…”

“…Due to its negligible effects on human health and the environment, tagatose has attracted the attention of the agricultural sector and showed promising efficacy in suppressing plant diseases caused by a wide range of phytopathogens, such as potato and tomato late blight ( Phytophthora infestans ), grapevine downy mildew ( Plasmopara viticola ), grapevine powdery mildew ( Erysiphe necator ) and cabbage downy mildew ( Hyaloperonospora parasitica ) [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. In particular, tagatose inhibited P. infestans growth in vitro [ 8 , 9 , 10 , 12 ] and reduces late blight symptoms on tomato plants under greenhouse conditions [ 14 , 15 ]. Tagatose inhibits sugar metabolism and mitochondrial processes of P. infestans [ 8 , 10 , 12 ], and it can activate grapevine resistance against downy mildew [ 16 , 17 ], suggesting multiple mechanisms of action against phytopathogens.…”