title: A Caleosin-Like Protein with Peroxygenase Activity Mediates Aspergillus flavus Development, Aflatoxin Accumulation, and Seed Infection.
abstract: Caleosins are a small family of calcium-binding proteins endowed with peroxygenase activity in plants. Caleosin-like genes are present in fungi; however, their functions have not been reported yet. In this work, we identify a plant caleosin-like protein in Aspergillus flavus that is highly expressed during the early stages of spore germination. A recombinant purified 32-kDa caleosin-like protein supported peroxygenase activities, including co-oxidation reactions and reduction of polyunsaturated fatty acid hydroperoxides. Deletion of the caleosin gene prevented fungal development. Alternatively, silencing of the gene led to the increased accumulation of endogenous polyunsaturated fatty acid hydroperoxides and antioxidant activities but to a reduction of fungal growth and conidium formation. Two key genes of the aflatoxin biosynthesis pathway, aflR and aflD, were downregulated in the strains in which A. flavus PXG (AfPXG) was silenced, leading to reduced aflatoxin B1 production in vitro. Application of caleosin/peroxygenase-derived oxylipins restored the wild-type phenotype in the strains in which AfPXG was silenced. PXG-deficient A. flavus strains were severely compromised in their capacity to infect maize seeds and to produce aflatoxin. Our results uncover a new branch of the fungal oxylipin pathway and may lead to the development of novel targets for controlling fungal disease.
authors.affiliation: Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), Damascus, Syria ashanano@aec.org.sy.
authors.forename: Abdulsamie
authors.initials: A
authors.lastname: Hanano
authors.affiliation: Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), Damascus, Syria.
authors.forename: Ibrahem
authors.initials: I
authors.lastname: Almousally
authors.affiliation: Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), Damascus, Syria.
authors.forename: Mouhnad
authors.initials: M
authors.lastname: Shaban
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Strasbourg, France.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Blee
mesh_terms: D000348:Aflatoxins / Q000378:metabolism*; D001231:Aspergillus flavus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D017353:Gene Deletion; D008054:Lipid Peroxides / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000382:microbiology*; D013172:Spores, Fungal / Q000254:growth & development*; D003313:Zea mays / Q000382:microbiology
chemical_list: D000348:Aflatoxins; D002135:Calcium-Binding Proteins; D005231:Fatty Acids, Unsaturated; D008054:Lipid Peroxides; D010940:Plant Proteins; C402836:caleosin protein, Sesamum indicum; D006899:Mixed Function Oxygenases; C022333:peroxygenase