Alternaria host-specific (HSTs) toxins: An overview of chemical characterization target sites regulation and their toxic effects

摘要

class="kwd-title">Abbreviations: SMs, secondary metabolites; HSTs, host specific toxins; nHSTs, non-host specific toxins; TEN, tentoxin; AOH, alternariol; AME, alternariol 9-monomethyl ether; ALT, alternuene; TeA, tenuazonic acid; ATX, alterotoxin; DHT, dihydrotentoxin; PKS, polyketide synthase gene; PCD, programmed cell death; NO, nitric oxide; ROS, reactive oxygen species; HR, hypersensitive response; H2O2, hydrogen peroxide; ¹O2, singlet oxygen; O2>˙ˉ, superoxide anion; >˙OH, hydroxyl radical; SOD, superoxide dismutase; GPX, guaiacol peroxidase; CAT, catalase; GR, glutathione reductase; APX, ascorbate peroxidase; MDHAR, monodehydroascorbate reductase; DHAR, dehydroascorbate reductase; GSH, glutathione; AA, ascorbic acid; CDCs, conditionally dispensable chromosomes; REMI, restriction enzyme-mediated integration; NRPS, nonribosomal peptide synthetase; UGT, UDP-Glucuronosyltransferases class="kwd-title">Keywords: Alternaria species, Secondary metabolites, Pathogenicity, Host-specific toxins, Non-host-specific toxins class="head no_bottom_margin" id="abs0015title">AbstractAlternaria causes pathogenic disease on various economically important crops having saprophytic to endophytic lifecycle. Pathogenic fungi of Alternaria species produce many primary and secondary metabolites (SMs). Alternaria species produce more than 70 mycotoxins. Several species of Alternaria produce various phytotoxins that are host-specific (HSTs) and non-host-specific (nHSTs). These toxins have various negative impacts on cell organelles including chloroplast, mitochondria, plasma membrane, nucleus, Golgi bodies, etc. Non-host-specific toxins such as tentoxin (TEN), Alternaric acid, alternariol (AOH), alternariol 9-monomethyl ether (AME), brefeldin A (dehydro-), Alternuene (ALT), Altertoxin-I, Altertoxin-II, Altertoxin-III, zinniol, tenuazonic acid (TeA), curvularin and alterotoxin (ATX) I, II, III are known toxins produced by Alternaria species. In other hand, Alternaria species produce numerous HSTs such as AK-, AF-, ACT-, AM-, AAL- and ACR-toxin, maculosin, destruxin A, B, etc. are host-specific and classified into different family groups. These mycotoxins are low molecular weight secondary metabolites with various chemical structures. All the HSTs have different mode of actions, biochemical reactions, and signaling mechanisms to causes diseases in the host plants. These HSTs have devastating effects on host plant tissues by affecting biochemical and genetic modifications. Host-specific mycotoxins such as AK-toxin, AF-toxin, and AC-toxin have the devastating effect on plants which causes DNA breakage, cytotoxic, apoptotic cell death, interrupting plant physiology by mitochondrial oxidative phosphorylation and affect membrane permeability. This article will elucidate an understanding of the disease mechanism caused by several Alternaria HSTs on host plants and also the pathways of the toxins and how they caused disease in plants.