title: Anacardic acid induces apoptosis-like cell death in the rice blast fungus Magnaporthe oryzae.
abstract: Anacardic acid (6-pentadecylsalicylic acid), extracted from cashew nut shell liquid, is a natural phenolic lipid well known for its strong antibacterial, antioxidant, and anticancer activities. Its effect has been well studied in bacterial and mammalian systems but remains largely unexplored in fungi. The present study identifies antifungal, cytotoxic, and antioxidant activities of anacardic acid in the rice blast fungus Magnaporthe oryzae. It was found that anacardic acid causes inhibition of conidial germination and mycelial growth in this ascomycetous fungus. Phosphatidylserine externalization, chromatin condensation, DNA degradation, and loss of mitochondrial membrane potential suggest that growth inhibition of fungus is mainly caused by apoptosis-like cell death. Broad-spectrum caspase inhibitor Z-VAD-FMK treatment indicated that anacardic acid induces caspase-independent apoptosis in M. oryzae. Expression of a predicted ortholog of apoptosis-inducing factor (AIF) was upregulated during the process of apoptosis, suggesting the possibility of mitochondria dependent apoptosis via activation of apoptosis-inducing factor. Anacardic acid treatment leads to decrease in reactive oxygen species rather than increase in reactive oxygen species (ROS) accumulation normally observed during apoptosis, confirming the antioxidant properties of anacardic acid as suggested by earlier reports. Our study also shows that anacardic acid renders the fungus highly sensitive to DNA damaging agents like ethyl methanesulfonate (EMS). Treatment of rice leaves with anacardic acid prevents M. oryzae from infecting the plant without affecting the leaf, suggesting that anacardic acid can be an effective antifungal agent.
authors.affiliation: Centre for Genome Research, Department of Microbiology and Biotechnology Centre, The M. S. University of Baroda, Vadodara, 390002, India.
authors.forename: Suhail
authors.initials: S
authors.lastname: Muzaffar
authors.affiliation: Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, 690525, India.
authors.forename: Chinchu
authors.initials: C
authors.lastname: Bose
authors.affiliation: Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, 690525, India.
authors.forename: Ashok
authors.initials: A
authors.lastname: Banerji
authors.affiliation: Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, 690525, India.
authors.forename: Bipin G
authors.initials: BG
authors.lastname: Nair
authors.affiliation: Centre for Genome Research, Department of Microbiology and Biotechnology Centre, The M. S. University of Baroda, Vadodara, 390002, India. bharat.chattoo@bcmsu.ac.in.
authors.forename: Bharat B
authors.initials: BB
authors.lastname: Chattoo
mesh_terms: D048729:Anacardic Acids / Q000302:isolation & purification / Q000633:toxicity*; D031021:Anacardium / Q000737:chemistry; D000935:Antifungal Agents / Q000302:isolation & purification / Q000633:toxicity*; D017209:Apoptosis; D016923:Cell Death; D020082:Magnaporthe / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D025282:Mycelium / Q000254:growth & development; D012275:Oryza / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D018515:Plant Leaves / Q000382:microbiology
chemical_list: D048729:Anacardic Acids; D000935:Antifungal Agents; C088115:anacardic acid
keywords: Anacardic acid; Antifungal agents; Apoptosis; Magnaporthe oryzae