Phytotoxic activity of grammicin produced by the fungus Xylaria grammica (Ascomycota) recovered from infected lesions on Handroanthus serratifolius (Bignoniaceae) leaves

Authors: BARRETO, DEBORA LUIZA - Universidade Federal De Minas Gerais; Cantrell, Charles; Reichley, Amber; Bajsa Hirschel, Joanna; Tamang, Prabin; Pan, Zhiqiang; BARICKMAN, THOMAS - Cornell University; PANDEY, PANKAJ - University Of Mississippi; CHITTIBOYINA, AMAR - University Of Mississippi; KHAN, SHABANA - University Of Mississippi; DUKE, STEPHEN - University Of Mississippi; DAYAN, FRANCK - Colorado State University; TRAXLER, CATHERINE - Colorado State University; CARVALHO, CAMILA - Universidade Federal De Minas Gerais; QUEIROZ, SONIA CLAUDIA - Embrapa; ROSA, LUIZ - Universidade Federal De Minas Gerais

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2026
Publication Date: 4/18/2026
Citation: Barreto, D.C., Cantrell, C.L., Reichley, A.C., Bajsa Hirschel, J.N., Tamang, P., Pan, Z., Barickman, T.C., Pandey, P., Chittiboyina, A.G., Khan, S.I., Duke, S.O., Dayan, F.E., Traxler, C., Carvalho, C.R., Queiroz, S.N., Rosa, L.H. 2026. Phytotoxic activity of grammicin produced by the fungus Xylaria grammica (Ascomycota) recovered from infected lesions on Handroanthus serratifolius (Bignoniaceae) leaves. Pest Management Science. https://doi.org/10.1002/ps.70803.
DOI: https://doi.org/10.1002/ps.70803

Interpretive Summary: A main challenge that modern agriculture faces is controlling pests of crops that significantly reduce yields. Left unchecked, these pests can cause billions of dollars in losses each year, jeopardizing food security. Consequently, the use of agricultural pesticides has become indispensable. However, continuous use of products with the same mechanisms of action has led to the selection of herbicide-resistant weed populations making the search for new products necessary. The Xylaria genus, classified under the fungal family Xylariaceae (Ascomycota), is recognized as a prolific source of secondary metabolites. We report the bioassay-guided isolation and identification of phytotoxic compounds from an extract of the fungus Xylaria grammica (Ascomycota), isolated from leaf lesions of seedlings of Handroanthus serratifolius (Bignoniaceae), from the Atlantic Rain Forest in Brazil. From the fungal crude extract, grammicin (1) and xylaric acid methyl ester (2) were purified. This is the first report unveiling the phytotoxicity of grammicin, which could serve as a scaffold for developing more potent herbicides with improved physicochemical properties.

Technical Abstract: We report the bioassay-guided isolation and identification of phytotoxic compounds from an extract of the fungus Xylaria grammica (Ascomycota), isolated from leaf lesions of seedlings of Handroanthus serratifolius (Bignoniaceae), from the Atlantic Rain Forest in Brazil. From the fungal crude extract, grammicin (1) and xylaric acid methyl ester (2) were purified and identified using one- and two-dimensional nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) analysis. Grammicin exhibited activity against Lactuca sativa (lettuce) and Agrostis stolonifera (bentgrass) at 1 mg mL-1, resulting in 100% inhibition of seed germination. Compound 2 had no activity against L. sativa but showed moderate activity against A. stolonifera, inhibiting seed germination at 1 mg mL-1. Against Lemna paucicostata (duckweed), grammicin inhibited growth by 50% (IC50) at 87.7 µM, while compound 2 had no activity. Neither compound had antifungal activity against the plant pathogen Colletotrichum fragariae. Grammicin is structurally similar to the natural compound patulin, which is reported to be phytotoxic by inhibition of photosystem II (PSII). Molecular modeling of the interaction of grammicin with the D1 protein of PSII predicts it to be a strong PSII inhibitor; however, in vivo testing indicated that it a very weak PSII inhibitor. In a panel of three mammalian cell lines, patulin was highly cytotoxic, whereas grammicin had no significant cytotoxicity. This is the first report unveiling the phytotoxicity of grammicin, which could serve as a scaffold for developing more potent herbicides with improved physicochemical properties.