Identification of a second family of genes in MOnilophthora perniciosa, thr causal agent of Witches Broom disease in caca, encoding necrosis inducing proteins similiar to cerato-platanins.
Zaparoli, G.; García, O.; Medrano, F. J.; Tibúrcio, R.; Barau, J. G.; Lacerda, G.; Pereira, G. A. G. Myccological Research. 113(1):61-72, Janeiro de 2009. Doi: 10.1016/j.mycres.2008.08.004 2008
The hemibiotrophic basidiomycete Moniliophthora perniciosa is the causal agent of witches’
broom disease in cacao. This is a dimorphic species, with monokaryotic hyphae during the
biotrophic phase, which is converted to dikaryotic mycelia during the saprophytic phase.
The infection in pod is characterized by the formation of hypertrophic and hyperplasic
tissues in the biotrophic phase, which is followed by necrosis and complete degradation
of the organ. We found at least five sequences in the fungal genome encoding putative
proteins similar to cerato-platanin (CP)-like proteins, a novel class of proteins initially
found in the phytopathogen Ceratocystis fimbriata. One M. perniciosa CP gene (MpCP1) was
expressed in vitro and proved to have necrosis-inducing ability in tobacco and cacao leaves.
The protein is present in solution as dimers and is able to recover necrosis activity after
heat treatment. Transcription analysis ex planta showed that MpCP1 is more expressed
in biotrophic-like mycelia than saprotrophic mycelia. The necrosis profile presented is
different from that caused by M. perniciosa necrosis and ethylene-inducing proteins
(MpNEPs), another family of elicitors expressed by M. perniciosa. Remarkably, a mixture
of MpCP1 with MpNEP2 led to a synergistic necrosis effect very similar to that found in
naturally infected plants. This is the first report of a basidiomycete presenting both
NEP1-like proteins (NLPs) and CPs in its genome.
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