Conidiophore Stalk-less1 Encodes a Putative Zinc-Finger Protein Involved in the Early Stage of Conidiation and Mycelial Infection in Magnaporthe oryzae

Abstract

Over recent decades, many pathogenicity genes of Magnaporthe oryzae have been identified but only a very limited number of genes have been identified that encode components of the conidiogenesis pathway. We report here a T-DNA insertional mutant that completely lost conidiation ability. Further investigation revealed that this mutant did not develop any conidiophore, and that the T-DNA was integrated into an annotated gene designated as conidiophore stalk-less1 or COS1. Complementation experiments suggested that COS1 may be a determinant of conidiation. Sequence analysis revealed that COS1 putatively encodes a 491-amino-acid zinc-finger protein and the protein was revealed localized to nucleus. Reverse-transcriptase polymerase chain reaction (RT-PCR)-based expression analysis indicated that two homologues of conidiophore-related genes were affected by the cos1 mutation, suggesting that Cos1 may function as a transcriptional regulator controlling genes responsible for conidiation. Inoculations of rice roots and wounded leaves with mycelia suggested that COS1 is not required for pathogenicity. Moreover, mutation of COS1 may aggravate infection of wounded leaves. Interestingly, different from the wild-type strain, mycelia of the cos1 mutant successfully infected host cells and caused visible symptoms on unwounded leaf blades and sheaths, indicating that Cos1 may have a role in some unknown mechanism of mycelial infection of M. oryzae.

Expression specificity of CBP1 is regulated by transcriptional repression during vegetative growth of Magnaporthe oryzae

“…The zinc finger transcription factor COS1 is involved in conidiophore stalk differentiation and conidiation (Zhou et al, 2009). The homeobox transcription factors MoHOX2 and MoHOX7 are involved in conidiation and appressorium formation, respectively (Kim et al, 2009).…”

Functional Analysis of the Pathogenicity-Related Gene VdPR1 in the Vascular Wilt Fungus Verticillium dahliae

“…Two novel binary vectors used in this study were constructed on the backbone of the pGKO 2 -gateway vector (deletion vector) [33] and the pSULPH-gfp vector (complementary vector) [34]. Table 1 shows the primers used for vector construction.…”

“…A 3.8 kb PCR product containing a 1.0 kb upstream sequence, the full-length VdPR1 gene coding region, and a 500 bp downstream sequence was amplified from Vd080 genomic DNA using the primers COM-F/R (Table 1). The product was cloned into the Xma I/ BsrG I sites of the binary vector pSULPH-gfp with lac promoter element, thereby conferring chlorimuron-ethy1 resistance and introducing the GFP gene [34]. The positive clones were named pSUL-VdPR1.…”

Isolation and functional analysis of the pathogenicity-related gene VdPR3 from Verticillium dahliae on cotton

“…A ~2.5 kb fragment including 1.2 kb upstream, VdPR3 (762 bp), and 500 bp downstream regions was amplified from the genomic DNA of strain Vd080 using primers COM-F and COM-R, which contained EcoRI and AF1II recognition site adaptors, respectively. The 2.5 kb fragment was cloned into the binary vector pSULPH-gfp carrying a chlorimuron-ethy1 resistance gene cassette and the green fluorescent protein (GFP) gene (Zhou et al 2009). The positive clones were named as pSUL-VdPR3.…”