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 Magnaporthe 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.

Expression of effector gene SIX1 of Fusarium oxysporum requires living plant cells

“…Some of these genes, like CgDN3 (Colletotrichum gloeosporioides), AVR9 (Cladosporium fulvum) and MPG1 (Magnaporthe grisea) are also upregulated during conditions of nitrogen starvation (Stephenson et al, 2000;Talbot et al, 1993;Van den Ackerveken et al, 1994). For Avr9 and Mpg1 it was shown that expression (partly) depends on a general nitrogen response factors (NRF1 and NPR1, respectively) (Lau and Hamer, 1996;Perez-Garcia et al, 2001;Soanes et al, 2002).…”

Qipgene inFusarium oxysporumis required for normal hyphae morphology and virulence

“…The primer pairs Qip-Up-2F/2R and Qip-Down-2F/2R were used to amplify two 0.9-kb fragments, which were used to test for homologous recombination. Wild-type A8 strain protoplasts were prepared as described previously (Talbot et al 1993). Protoplasts were transformed with the knockout plasmid pKO-Qip using a PEG-CaCl 2 -mediated procedure (Nakayashiki et al 1999).…”

Promoter trapping in Magnaporthe grisea

“…grisea strain Guy11 was used as wild type and cultured in complete medium (CM) as described previously (Talbot et al, 1993). Escherichia coli strain DH5α was used as a host for plasmid amplification.…”

“…Protoplasts isolation was carried out as described by Talbot et al(1993) with minor modifications. Briefly, a 3-cm 2 square of Guy11 mycelia was cut from the surface of the CM agar plate, incubated in 300 ml liquid CM medium at 28 °C on a rotary shaker at 125 r/min for 48 h. The mycelia were harvested by filtration and protoplasts were produced by Glucanex (Denmark) digestion in 0.7 mol/L NaCl.…”

“…Fungal genomic DNA was extracted as described by Talbot et al(1993). For confirmation of stable integration of the promoter trapping vector, 623 bp eGFP coding region was amplified using eGFP specific PCR and the genomic DNA of transformants as template.…”