Action of the fungal compound citrinin, a bioherbicide candidate, on photosystem II

Abstract

BACKGROUNDBioherbicides are becoming more attractive as safe weed control tools towards sustainable agriculture. Natural products constitute an important source chemicals and chemical leads for discovery and development of novel pesticide target sites. Citrinin is a bioactive compound produced by fungi of the genera Penicillium and Aspergillus. However, its physiological‐biochemical mechanism as a phytotoxin remains unclear.RESULTSCitrinin causes visible leaf lesions on Ageratina adenophora similar to those produced by the commercial herbicide bromoxynil. Phytotoxicity bioassay tests using 24 plant species confirmed that citrinin has a broad activity spectrum and therefore has potential as a bioherbicide. Based on chlorophyll fluorescence studies, citrinin mainly blocks PSII electron flow beyond plastoquinone QA at the acceptor side, resulting in the inactivation of PSII reaction centers. Furthermore, molecular modeling of citrinin docking to the A. adenophora D1 protein suggests that it binds to the plastoquinone QB site by a hydrogen bond between the O1 hydroxy oxygen atom of citrinin and the histidine 215 of the D1 protein, the same way as classical phenolic PSII herbicides do. Finally, 32 new citrinin derivatives were designed and sorted according to free energies on the basis of the molecular model of an interaction between the citrinin molecule and the D1 protein. Five of the modeled compounds had much higher ligand binding affinity within the D1 protein compared with lead compound citrinin.CONCLUSIONCitrinin is a novel natural PSII inhibitor that has the potential to be developed into a bioherbicide or utilized as a lead compound for discovery of new derivatives with high herbicidal potency. © 2023 Society of Chemical Industry.

Structure-Based Design, Virtual Screening, and Discovery of Novel Patulin Derivatives as Biogenic Photosystem II Inhibiting Herbicides

“…On the basis of this method, two novel TeA analogues possessing higher herbicidal activity were discovered [ 26 ]. Yang et al elucidated the mode of action of mycotoxin citrinin, and furtherly screened five new citrinin derivatives by introducing different substituents at the 9-position with high herbicidal potency compared with lead compound citrinin based on a computer-aided design strategy [ 27 ]. To find novel patulin derivatives with improved potency, QED values and binding interaction energy of 81 novel compounds were designed based on the modification of substituents in 1-, C3, C4, 5-, C6, or C7 positions of patulin binding to the Q B site and are displayed ( Table 1 , Table 2 , Table 3 , Table 4 , Table 5 and Table 6 ).…”

The future of microbial bioherbicides

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Four related articles from non-participants are also included. [18][19][20][21] The article by Duke gives the rationale for the meeting, discussing the many microbial bioherbicides that have failed and detailing the technical and economic reasons for lack of success. 2 He makes a case of the use of killed microbial preparations for weed control, as such products avoid many of the efficacy and safety issues of live organisms.…”

“…Several phytotoxins, including a first reported compound from the plant pathogen Curvularia inaequalis, were evaluated by Wei et al 20 as potential herbicides. The mode of action of the microbial compound radulanin A as a photosystem II (PSII) inhibitor was elucidated, 19 and the action of citrinin, a secondary product of Penicillium and Aspergillis species on PSII was determined by Yang et al 21 The main intent of the conference was to enable some of the major exponents of the scientific community working with different weed biological control agents (fungi, bacteria, viruses) and having various backgrounds (biology, formulation, genetics, risk assessment, biochemistry, ecology, physiology, agronomy, nanotechnology, and application technology) to meet and interact. Also, scientists working on the same types of microorganisms, but with different purposes, could exchange ideas.…”

“…Sixteen of the articles in this issue are from conference participants 2–17 . Four related articles from non‐participants are also included 18–21 . The article by Duke gives the rationale for the meeting, discussing the many microbial bioherbicides that have failed and detailing the technical and economic reasons for lack of success 2 .…”

“…as potential herbicides. The mode of action of the microbial compound radulanin A as a photosystem II (PSII) inhibitor was elucidated, 19 and the action of citrinin, a secondary product of Penicillium and Aspergillis species on PSII was determined by Yang et al 21 …”