Identification and Characterization of MPG1, a Gene Involved in Pathogenicity from the Rice Blast Fungus Magnaporthe grisea

Abstract

Differential cDNA cloning was used to identify genes expressed during infectious growth of the fungal pathogen Mag-naporthe grisea in its host, the rice plant. We characterized one of these genes, MPG1, in detail. Using a nove1 assay to determine the proportion of fungal biomass present in the plant, we determined that the MPGl transcript was 60-fold more abundant during growth in the plant than in culture. Mpgl mutants have a reduced ability to cause disease symptoms that appears to result from an impaired ability to undergo appressorium formation. MPGl mRNA was highly abundant very early in plant infection concomitant with appressorium formation and was also abundant at the time of symptom development. The MPGl mRNA was also expressed during conidiation and i n mycelial cultures starved for nitrogen or carbon. MPGl potentially encodes a small, secreted, cysteine-rich, moderately hydrophobic protein with the characteristics of a fungal hydrophobin. Consistent with the role of the MPGl gene product as a hydrophobin, Mpgl mutants show an basily wettable" phenotype. Our results suggest that hydrophobins may have a role in the elaboration of infective structures by fungi and may fulfill other functions in fungal phytopathogenesis.

Investigating chitin deacetylation and chitosan hydrolysis during vegetative growth in Magnaporthe oryzae

“…Strain maintenance and composition of media were essentially as described by Talbot et al (Talbot, Ebbole, & Hamer, 1993). For evaluating growth of strains on solid media under stress conditions, CM was supplemented with different treatments as follows: 40 μg/ml CFW, 100 μg/ml Congo Red, 5 mM H 2 O 2 , 1 M sorbitol, 2.5 mM caffeine, 2 g/L CuSO 4 , 0.005% ( w / v ) SDS, or 1 M NaCl.…”

“…The final PCR products were used directly for DNA‐mediated protoplast transformation of WT Guy11 strain following protocols described by Talbot et al (Talbot et al . , 1993). Putative transformants were selected on minimal medium supplemented with 300 μg/ml hygromycin B (Calbiochem, Merck, Darmstadt, Germany) or defined complex medium supplemented with 60 μg/ml bialaphos (Goldbio, St. Louis, MO, USA).…”

Proteomic analysis of dimorphic transition in the phytopathogenic fungus Ustilago maydis

“…Nitrogen starvation has been shown to be one of the environmental cues for disease development in planta in a number of different fungi (reviewed in [30]). Multiple genes are induced both by nitrogen starvation and in planta, as shown in Cladosporium fulvum [31], Magnaporthe grisea [32] and Colletotrichum gloeosporioides [33]. A direct link between nitrogen starvation and morphology exists in S. cerevisiae, where nitrogen starvation causes a pseudohyphal, invasive growth pattern [34].…”

Regulatory network of genes associated with stimuli sensing, signal transduction and physiological transformation of appressorium inMagnaporthe oryzae

“…Aerial hyphae with compromised surface hydrophobicity are highly wettable. For instance, the deletion of MHP 1 and MPG 1 in M. oryzae triggered the formation of highly wettable hyphae in the respective mutant strains (Talbot et al 1993; Kim et al 2005); a similar phenotype was observed in Fusarium graminearum ∆ hyd5 strains (Minenko et al 2014), and Trichoderma reesei ∆ trhfb3 strains (He et al 2017). However, the deletion of three hydrophobin encoding genes BHP 1, BHP 2 and BHP 3 in Botrytis cinerea did not alter the surface hydrophobicity of conidia and hyphae produced by the respective gene deletion mutants (Terhem and Van Kan 2014).…”

“…For instance, MPG 1 and MHP 1 essentially promote sporulation and full virulence of M. oryzae (Talbot et al 1993; Kim et al 2005). Northern blot analysis showed a higher induction of MPG 1 during early (12 hpi) and late (96 hpi) stages of plant infection (Talbot et al 1993); however, MHP1 only showed enhanced expression activities at late stages (96 and 120 hpi of infection) (Kim et al 2005). …”