title: MoTea4-mediated polarized growth is essential for proper asexual development and pathogenesis in Magnaporthe oryzae.
abstract: Polarized growth is essential for cellular development and function and requires coordinated organization of the cytoskeletal elements. Tea4, an important polarity determinant, regulates localized F-actin assembly and bipolar growth in fission yeast and directional mycelial growth in Aspergillus. Here, we characterize Tea4 in the rice blast fungus Magnaporthe oryzae (MoTea4). Similar to its orthologs, MoTea4-green fluorescent protein (MoTea4-GFP) showed punctate distribution confined to growth zones, particularly in the mycelial tips, aerial hyphae, conidiophores, conidia, and infection structures (appressoria) in Magnaporthe. MoTea4 was dispensable for vegetative growth in Magnaporthe. However, loss of MoTea4 led to a zigzag morphology in the aerial hyphae and a huge reduction in conidiation. The majority of the tea4Delta conidia were two celled, as opposed to the tricellular conidia in the wild type. Structure-function analysis indicated that the SH3 and coiled-coil domains of MoTea4 are necessary for proper conidiation in Magnaporthe. The tea4Delta conidia failed to produce proper appressoria and consequently failed to infect the host plants. The tea4Delta conidia and germ tubes showed disorganized F-actin structures with significantly reduced numbers of cortical actin patches. Compared to the wild-type conidia, the tea4Delta conidia showed aberrant germination, poor cytoplasmic streaming, and persistent accumulation of lipid droplets, likely due to the impaired F-actin cytoskeleton. Latrunculin A treatment of germinating wild-type conidia showed that an intact F-actin cytoskeleton is indeed essential for appressorial development in Magnaporthe. We show that MoTea4 plays an important role in organizing the F-actin cytoskeleton and is essentially required for polarized growth and morphogenesis during asexual and pathogenic development in Magnaporthe.
authors.affiliation: Fungal Patho-Biology Group, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604, Republic of Singapore.
authors.forename: Rajesh N
authors.initials: RN
authors.lastname: Patkar
authors.forename: Angayarkanni
authors.initials: A
authors.lastname: Suresh
authors.forename: Naweed I
authors.initials: NI
authors.lastname: Naqvi
mesh_terms: D000199:Actins / Q000378:metabolism; D016764:Cell Polarity; D003595:Cytoplasmic Streaming; D003599:Cytoskeleton / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D017353:Gene Deletion; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020082:Magnaporthe / Q000166:cytology / Q000254:growth & development* / Q000472:pathogenicity*; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D010641:Phenotype; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012100:Reproduction, Asexual / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D014774:Virulence
chemical_list: D000199:Actins; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; C501888:Tea4 protein, S pombe; D049452:Green Fluorescent Proteins
references.citation: Nature. 2003 Jun 5;423(6940):647-51
references.pmid: 12789340
references.citation: Biol Cell. 2006 Nov;98(11):619-31
references.pmid: 17042740
references.citation: Mol Biol Cell. 2008 Jan;19(1):339-51
references.pmid: 18003978
references.citation: J Cell Biol. 1996 Nov;135(3):725-39
references.pmid: 8909546
references.citation: Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
references.pmid: 9254694
references.citation: Eukaryot Cell. 2007 Dec;6(12):2240-50
references.pmid: 17933908
references.citation: Dev Cell. 2007 Jun;12(6):987-96
references.pmid: 17543869
references.citation: Biochem Soc Trans. 2005 Dec;33(Pt 6):1247-9
references.pmid: 16246089
references.citation: J Cell Sci. 2005 Jul 1;118(Pt 13):2935-47
references.pmid: 15976451
references.citation: Fungal Genet Biol. 2009 Jun-Jul;46(6-7):450-60
references.pmid: 19298860
references.citation: Dev Cell. 2005 Apr;8(4):479-91
references.pmid: 15809031
references.citation: Curr Biol. 2008 Nov 25;18(22):1748-53
references.pmid: 19026544
references.citation: EMBO J. 1994 May 1;13(9):2066-74
references.pmid: 8187760
references.citation: J Cell Sci. 2007 May 1;120(Pt 9):1584-95
references.pmid: 17405809
references.citation: Eukaryot Cell. 2008 Jan;7(1):102-11
references.pmid: 18039945
references.citation: J Plant Res. 2007 Jan;120(1):31-43
references.pmid: 17252175
references.citation: Curr Biol. 2008 Mar 11;18(5):322-30
references.pmid: 18328707
references.citation: Genes Dev. 1998 May 1;12(9):1356-70
references.pmid: 9573052
references.citation: J Cell Biol. 2004 Jun 7;165(5):697-707
references.pmid: 15184402
references.citation: Cold Spring Harb Symp Quant Biol. 1995;60:729-44
references.pmid: 8824448
references.citation: Protoplasma. 2003;222(3-4):211-5
references.pmid: 14714210
references.citation: Eukaryot Cell. 2009 Jul;8(7):957-67
references.pmid: 19429780
references.citation: Curr Opin Microbiol. 2002 Aug;5(4):366-71
references.pmid: 12160854
references.citation: Curr Biol. 2001 Jun 5;11(11):836-45
references.pmid: 11516644
references.citation: Autophagy. 2009 Jan;5(1):33-43
references.pmid: 19115483
references.citation: EMBO J. 2005 Nov 2;24(21):3690-9
references.pmid: 16222337
references.citation: Mol Microbiol. 2006 Jul;61(1):61-75
references.pmid: 16824095
references.citation: Plant Cell. 2004 Jun;16(6):1564-74
references.pmid: 15155882