Inhibition of Signal Transduction Leading to Appressorium Formation in Magnaporthe Grisea by Glisoprenins

Author(s):  
E. Thines ◽  
F. Eilbert ◽  
H. Anke ◽  
O. Sterner
2001 ◽  
Vol 14 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Young Soon Kim ◽  
Hyun Hwa Lee ◽  
Moon Kyung Ko ◽  
Chae Eun Song ◽  
Cheol-Yong Bae ◽  
...  

A pepper esterase gene (PepEST) that is highly expressed during an incompatible interaction between pepper (Capsicum annuum) and the anthracnose fungus Colletotrichum gloeosporioides has been previously cloned. Glutathione-S-transferase-tagged recombinant PepEST protein expressed in Escherichia coli showed substrate specificity for p-nitrophenyl esters. Inoculation of compatible unripe pepper fruits with C. gloeosporioides spores amended with the recombinant protein did not cause anthracnose symptoms on the fruit. The recombinant protein has no fungicidal activity, but it significantly inhibits appressorium formation of the anthracnose fungus in a dose-dependent manner. An esterase from porcine liver also inhibited appressorium formation, and the recombinant protein inhibited appressorium formation in the rice blast fungus, Magnaporthe grisea. Inhibition of appressorium formation in M. grisea by the recombinant protein was reversible by treatment with cyclic AMP (cAMP) or 1,16-hexadecanediol. The results suggest that the recombinant protein regulates appressorium formation by modulating the cAMP-dependent signaling pathway in this fungus. Taken together, the PepEST esterase activity can inhibit appressorium formation of C. gloeosporioides, which may result in protection of the unripe fruit against the fungus.


PROTEOMICS ◽  
2004 ◽  
Vol 4 (11) ◽  
pp. 3579-3587 ◽  
Author(s):  
Sun Tae Kim ◽  
Seok Yu ◽  
Sang Gon Kim ◽  
Han Ju Kim ◽  
Sun Young Kang ◽  
...  

1997 ◽  
Vol 10 (9) ◽  
pp. 1075-1086 ◽  
Author(s):  
Shaohua Liu ◽  
Ralph A. Dean

Three G protein α subunit genes have been cloned and characterized from Magnaporthe grisea: magA is very similar to CPG-2 of Cryphonectria parasitica; magB is virtually identical to CPG-1 of Cryphonectria parasitica, to gna1 of Neurospora crassa, and to fadA of Emericella nidulans; and magC is most similar to gna2 of Neurospora crassa. Homologous recombination resulting in targeted deletion of magA had no effect on vegetative growth, conidiation, or appressorium formation. Deletion of magC reduced conidiation, but did not affect vegetative growth or appressorium formation. However, disruption of magB significantly reduced vegetative growth, conidiation, and appressorium formation. magB¯ transformants, unlike magA¯ and magC¯ transformants, exhibited a reduced ability to infect and colonize susceptible rice leaves. G protein α subunit genes are required for M. grisea mating. magB¯ transformants failed to form perithecia, whereas magA¯ and magC¯ transformants did not produce mature asci. These results suggest that G protein α subunit genes are involved in signal transduction pathways in M. grisea that control vegetative growth, conidiation, conidium attachment, appressorium formation, mating, and pathogenicity.


1998 ◽  
Vol 88 (1) ◽  
pp. 58-62 ◽  
Author(s):  
Woo-Bong Choi ◽  
Shin-Ho Kang ◽  
Yin-Won Lee ◽  
Yong-Hwan Lee

Magnaporthe grisea, the causal agent of rice blast, forms a dome-shaped melanized infection structure, an appressorium, to infect its host. Environmental cues that induce appressorium formation in this fungus include the hydrophobicity and hardness of the contact surface and chemicals produced by the host. An elevated concentration of intracellular cyclic AMP (cAMP) has been implicated in appressorium differentiation in M. grisea. Polyamines (putrescine, spermidine, and sper-mine) are involved in cell growth and differentiation in a wide range of organisms. To understand the role of polyamines in appressorium differentiation in M. grisea, intracellular polyamines were quantified, and the effects of polyamines and polyamine biosynthesis inhibitors on conidial germination and appressorium formation were tested. High levels of polyamines were detected in freshly collected spores, but the levels decreased during conidial germination. Spermidine was found to be the major component. Polyamines and polyamine biosynthesis inhibitors did not affect conidial germination, but polyamines specifically impaired appressorium formation. Furthermore, exogenous addition of cAMP restored appressorium formation inhibited by poly-amines. These results suggest that polyamines may reduce intracellular cAMP levels in M. grisea, leading to the inhibition of appressorium formation.


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