title: Growth inhibition and excessive branching in Aphanomyces cochlioides induced by 2,4-diacetylphloroglucinol is linked to disruption of filamentous actin cytoskeleton in the hyphae.
abstract: We observed that 2,4-diacetylphloroglucinol (DAPG), a major antimicrobial metabolite produced by a rhizoplane bacterium Pseudomonas fluorescens ECO-001 inhibited mycelial growth of a damping-off phytopathogen Aphanomyces cochlioides AC-5 through inducing excessive branching and curling in the hyphae. This study aimed to unravel the mode of action of DAPG caused excessive branching, curling and growth inhibition of AC-5 hyphae by detecting localized changes in the cortical filamentous actin (F-actin) organization by rhodamine-conjugated phalloidin. Confocal laser scanning microscopic observations revealed that both living bacteria and DAPG severely disrupted the organization of F-actin in the A. cochlioides hyphae in a similar manner. Furthermore, an inhibitor of F-actin polymerization, latrunculin B also induced similar growth inhibition, excessive branching and caused disruption of F-actin in the AC-5 hyphae. Our results suggested that growth inhibition and excessive branching induced in A. cochlioides by DAPG is likely to be linked to the disruption of F-actin cytoskeleton in the affected hyphae. This is the first report on disruption of cytoskeleton of a eukaryotic A. cochlioides by a well-known biocontrol metabolite DAPG secreted from a prokaryotic bacterium ECO-001.
authors.affiliation: Laboratory of Ecological Chemistry, Graduate School of Agriculture, Hokkaido University, Kita-Ku, Sapporo, 060-8589, Japan, tofazzalislam@yahoo.com.
authors.forename: Md Tofazzal
authors.initials: MT
authors.lastname: Islam
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Fukushi
references.citation: Biochem Pharmacol. 2002 Jun 1;63(11):1979-88
references.pmid: 12093474
references.citation: Plant Cell. 1999 Dec;11(12):2331-47
references.pmid: 10590162
references.citation: Proc Natl Acad Sci U S A. 2008 Sep 23;105(38):14585-90
references.pmid: 18794525
references.citation: J Appl Microbiol. 2006 May;100(5):926-37
references.pmid: 16629993
references.citation: Annu Rev Phytopathol. 1999;37:175-196
references.pmid: 11701821
references.citation: Plant Physiol. 2004 Dec;136(4):3864-76
references.pmid: 15591444
references.citation: Biosci Biotechnol Biochem. 2001 Sep;65(9):1933-48
references.pmid: 11676003
references.citation: Science. 2002 Jun 21;296(5576):2229-32
references.pmid: 12077418
references.citation: J Cell Sci. 1998 Jul 30;111 ( Pt 14):2005-16
references.pmid: 9645948
references.citation: Cell Motil Cytoskeleton. 2008 Jul;65(7):553-62
references.pmid: 18412254
references.citation: Nat Rev Mol Cell Biol. 2004 Aug;5(8):635-46
references.pmid: 15366707
references.citation: J Cell Biol. 1985 Apr;100(4):1173-84
references.pmid: 3980581
references.citation: Phytopathology. 2003 Aug;93(8):966-75
references.pmid: 18943863
references.citation: J Agric Food Chem. 2000 May;48(5):1882-7
references.pmid: 10820109
references.citation: J Bacteriol. 1999 May;181(10):3155-63
references.pmid: 10322017
references.citation: Toxicon. 1996 Aug;34(8):937-45
references.pmid: 8875780
references.citation: Int J Antimicrob Agents. 2003 Nov;22(5):545-7
references.pmid: 14602377
references.citation: Nat Rev Mol Cell Biol. 2004 Jun;5(6):471-80
references.pmid: 15173826
references.citation: Mol Plant Microbe Interact. 2008 Oct;21(10):1349-58
references.pmid: 18785830
references.citation: Fungal Genet Biol. 2000 Jun;30(1):45-62
references.pmid: 10955907
references.citation: Int J Antimicrob Agents. 2003 Jan;21(1):71-4
references.pmid: 12507841