Identification of Fcl-29 as an Effective Antifungal Natural Product against Fusarium graminearum and Combinatorial Engineering Strategy for Improving Its Yield

Abstract

Fusarium head blight (FHB), caused by Fusarium graminearum, whose occurrence and prevalence causes 10–70% wheat production loss, is one of the most destructive diseases influencing the production of wheat globally. To identify the potential natural products (NPs) against F. graminearum, we screened 59 Xenorhabdus strains and discovered that the cell-free supernatant (CFS) of X. budapestensis 14 (XBD14) displays the highest bioactivity. Multiple genetic methods coupled with HRMS/MS analysis determined the major antifungal NP to be Fcl-29, a fabclavine derivative. Fcl-29 was found to effectively control FHB of wheat in the field test and demonstrated broad-spectrum antifungal activity against important pathogenic fungi. The production of Fcl-29 was dramatically improved by 33.82-fold with the combinatorial strategy of genetic engineering (1.66-fold) and fermentation engineering (20.39-fold). The exploration of a new biofungicide in global plant protection is now possible.

Development of an Efficient and Seamless Genetic Manipulation Method for Xenorhabdus and Its Application for Enhancing the Production of Fabclavines

“…nematophila CB6 and a longer one in X. budapestensis XBD8 (47,788 bp, fclA – fclN ), both of which are unnecessary for cell growth, ,, were selected for seamless deletion. The results demonstrated successful deletion of fclA – N in X.…”

“…Fabclavines show broad-spectrum bioactivity against bacteria, fungi, protozoa, and insects. ,, Recently, we had identified fabclavine-29 (Fcl-29) in X. budapestensis XBD14, and fabclavine-7 (Fcl-7) and fabclavine-8 (Fcl-8) in X. budapestensis XBD8, as well as the highly conserved biosynthetic gene cluster (BGC).…”

“…These compounds serve as weapons for Xenorhabdus to kill the host insect and to compete with potential microorganisms, for instance, Xanthomonas campestris, Ralstonia solanacearum, Pseudomonas syringae, Bacillus subtilis, Erwinia amylovora etc., in the environment. ,− Fabclavines are one of the representative NPs produced by Xenorhabdus species, which are a group of polyketide-peptide-polyamino compounds biosynthesized by a hybrid nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) cluster (NRPS-PKS cluster) (Figure S1a). They exhibit broad-spectrum antifungal activity against various plant pathogens, including Fusarium graminearum, Pyricularia oryzae, Rhizoctonia solanikuhn, Alternaria solani, etc . Xenocoumacin 1 (Xcn1) is another highly efficient antimicrobial NP produced by Xenorhabdus spp., which exhibits excellent control properties against plant phytophthora blight, , and it is also biosynthesized by a hybrid NRPS-PKS cluster (Figure S1b).…”

“…They exhibit broad-spectrum antifungal activity against various plant pathogens, including Fusarium graminearum, Pyricularia oryzae, Rhizoctonia solanikuhn, Alternaria solani, etc. 12 Xenocoumacin 1 (Xcn1) is another highly efficient antimicrobial NP produced by Xenorhabdus spp., which exhibits excellent control properties against plant phytophthora blight, 13,14 and it is also biosynthesized by a hybrid NRPS-PKS cluster (Figure S1b). Moreover, multiple valuable NPs, such as Game-Xpeptides, xenotetrapeptide, rhabdopeptide, odilorhabdin and indole derivatives, etc., have also been identified from this type of bacteria.…”

Venturicidin A Is a Potential Fungicide for Controlling Fusarium Head Blight by Affecting Deoxynivalenol Biosynthesis, Toxisome Formation, and Mitochondrial Structure

“…Fusarium head blight (FHB) is mainly caused by the ascomycete fungus Fusarium graminearum, which is a destructive pathogen of cereal crops globally. , When the environment is favorable, FHB epidemics cause considerable loss in grain and contaminate grains with mycotoxins, , including deoxynivalenol (DON), its acetylated derivatives (3AcDON, 15AcDON), and nivalenol (NIV), which are carcinogenic to humans and animals . DON is a vital virulence factor produced during pathogenesis, and trichothecene ( TRI ) genes are responsible for its biosynthesis. , In China, FHB is prevalent in the Yangtze River Valley, Huaihe River valleys, and the eastern coastal region.…”