%D 2008 %0 In-Process %T Magnaporthe grisea avirulence gene ACE1 belongs to an infection-specific gene cluster involved in secondary metabolism . %J New Phytol %V 179 %P 196-208 %A Collemare J %A Pianfetti M %A Houlle AE %A Morin D %A Camborde L %A Gagey MJ %A Barbisan C %A Fudal I %A Lebrun MH %A Bohnert HU %M pub18433432 %X The avirulence gene ACE1 from the rice blast fungus Magnaporthe grisea encodes a polyketide synthase ( PKS ) fused to a nonribosomal peptide synthetase ( NRPS ) probably involved in the biosynthesis of a secondary metabolite recognized by Pi33 resistant rice ( Oryza sativa ) cultivars . Analysis of the M grisea genome revealed that ACE1 is located in a cluster of 15 genes , of which 14 are potentially involved in secondary metabolism as they encode enzymes such as a second PKS-NRPS ( SYN2 ) , two enoyl reductases ( RAP1 and RAP2 ) and a putative Zn ( II ) ( 2 ) Cys ( 6 ) transcription factor ( BC2 ) . These 15 genes are specifically expressed during penetration into the host plant , defining an infection-specific gene cluster . A pORF3-GFP transcriptional fusion showed that the highly expressed ORF3 gene from the ACE1 cluster is only expressed in appressoria , as is ACE1 . Phenotypic analysis of deletion or disruption mutants of SYN2 and RAP2 showed that they are not required for avirulence in Pi33 rice cultivars , unlike ACE1 . Inactivation of other genes was unsuccessful because targeted gene replacement and disruption were inefficient at this locus . Overall , the ACE1 gene cluster displays an infection-specific expression pattern restricted to the penetration stage which is probably controlled at the transcriptional level and reflects regulatory networks specific to early stages of infection .