Double Gamers—Can Modified Natural Regulators of Higher Plants Act as Antagonists against Phytopathogens? The Case of Jasmonic Acid Derivatives

Abstract

As key players in biotic stress response of plants, jasmonic acid (JA) and its derivatives cover a specific and prominent role in pathogens-mediated signaling and hence are promising candidates for a sustainable management of phytopathogenic fungi. Recently, JA directed antimicrobial effects on plant pathogens has been suggested, supporting the theory of oxylipins as double gamers in plant-pathogen interaction. Based on these premises, six derivatives (dihydrojasmone and cis-jasmone, two thiosemicarbazonic derivatives and their corresponding complexes with copper) have been evaluated against 13 fungal species affecting various economically important herbaceous and woody crops, such as cereals, grapes and horticultural crops: Phaeoacremonium minimum, Neofusicoccum parvum, Phaeomoniella chlamydospora, Fomitiporia mediterranea, Fusarium poae, F. culmorum, F. graminearum, F. oxysporum f. sp. lactucae,F. sporotrichioides, Aspergillus flavus, Rhizoctonia solani,Sclerotinia spp. and Verticillium dahliae. The biological activity of these compounds was assessed in terms of growth inhibition and, for the two mycotoxigenic species A. flavus and F. sporotrichioides, also in terms of toxin containment. As expected, the inhibitory effect of molecules greatly varied amongst both genera and species; cis-jasmone thiosemicarbazone in particular has shown the wider range of effectiveness. However, our results show that thiosemicarbazones derivatives are more effective than the parent ketones in limiting fungal growth and mycotoxins production, supporting possible applications for the control of pathogenic fungi.

The AFLATOX® Project: Approaching the Development of New Generation, Natural-Based Compounds for the Containment of the Mycotoxigenic Phytopathogen Aspergillus flavus and Aflatoxin Contamination

“…A great variability of efficacy was observed amongst compounds: derivatives from benzaldehyde, benzophenone, cuminaldehyde, cinnamaldehyde, 2-acetylthiophene and cis -jasmone parent compounds proved to be the most active compounds ( Tables S1 and S2 ) [ 23 , 27 , 29 , 32 , 33 , 34 ], while many others did not show any interesting activity.…”

“…In turn, the pre-existing biological activity could be enhanced by specific structural modifications. Several researches have proposed natural compounds or their chemical analogues as crop-protective agents; additionally, metallic ions such as copper and zinc have been long time used for their fungicidal properties, demonstrating containment effects on the growth of phytopathogenic fungi and mycotoxins production [ 27 , 29 , 34 ]. In our study, we screened an extended panel of natural compounds and synthesized derivatives in order to individuate—and possibly ameliorate—effective antifungal and/or anti-aflatoxigenic molecules against A. flavus , being reasonably safe for the health of the stakeholders and the environment.…”

“…On the other hand, if this observation was confirmed also by Cu and Zn complexes of 2-acfuTS, that both resulted more active in lowering AFs production than their ligand, it apparently contrasts with what has been obtained with 2-actpTS-Cu and-Zn, as effective as 2-actpTS. However, the hypothesis of the copper ion thought to be the redox active center of thiosemicarbazone compounds—in terms of both antifungal and anti-mycotoxigenic effect—has been already confuted (as in the case of cis - and dihydrojasmone thiosemicarbazones [ 34 ]), being suggested to mainly rely on the features of parent molecules. Hence, if purposive modifications could be applied in order to raise the molecules selectivity and their activity power, the in vivo validation should be performed each time.…”

“…Interestingly, amongst all the screened TSs, the highest number of biologically active compounds refers to anti-aflatoxigenic molecules, indicating that probably the majority of molecular/cellular targets belong to secondary metabolism pathways, and thus only in few cases they might severely affect the fungal growth. More remarkably, some molecules were found to show anti-toxigenic potential uncoupled with a significant effect on mycelium development [ 23 , 33 , 34 , 50 ], this is considered particularly interesting in an ecological perspective overall. These selective anti-aflatoxigenic compounds could become considerably interesting for applications aimed at excluding ordinary fungicidal, nonspecific agents.…”

Bryo-Activities: A Review on How Bryophytes Are Contributing to the Arsenal of Natural Bioactive Compounds against Fungi

“…LC-based lipidomics is relatively rapid and usually requires less sample than GC-derived methods, since only 2–10 mg of leaf dry weight is needed, but these advanced techniques only recently have been applied on bryophytes extracts: in 2017, Gacet and coauthors employed targeted metabolomics using LC–MS/MS and GC–MS to study signaling lipids in 71 plant species, representative of major phylogenetic clades, to systematically investigate the distribution of lipids in the plant kingdom; they found a fascinating positive phylogenetic correlation in the jasmonic acid (JA) abundance of early plants versus Angiosperms and Gymnosperms [ 194 ]. JA and its derivatives, jasmonates, belong to the class of oxylipins, bioactive metabolites derived from the oxygenation of acidic polyunsaturated fats [ 195 ]: besides primarily exerting regulatory functions involved in plant reproductive development and vegetative growth, jasmonates not only play critical roles in the defense response against wounds and attacks by pathogens, but also have been recently reported to possess a direct antifungal activity against a number of fungal phytopathogens [ 196 ]. Gachet et al demonstrated that, while completely absent in algae, JA started to be detected in small to intermediate amounts in bryophytes (namely: hornworts Anthoceros agrestis, Anthoceros punctatus and Phaeoceros laevis ; mosses Physcomitrella patens, Funaria hygrometrica, Polytrichum juniperinum, Hedwigia ciliata and Hylocomium splendens and liverworts Conocephalum conicum, Marchantia polymorpha and Riccia fluitans ), with the ending to be more represented in higher plants.…”