G-Proteins as Molecular Switches in Signal Transduction - PAMP Signals in Plant Innate Immunity: Signal Perception and Transduction - page 194

biosynthesis) (Fujiwara et al. 2006 ). Cinnamoyl-CoA reductase, a key enzyme in
lignin biosynthesis, is activated by Rac1 in rice (Kawasaki et al. 2006 ). The G-protein
would have activated the phenylpropanoid pathway, probably by triggering MAPK
signaling system (Lieberherr et al. 2005 ; Fujiwara et al. 2006 ). Silencing of the rice
MAPK, OsMAPK6, reduced the level of phenylalanine ammonia-lyase ( PA L )
mRNA in rice (Lieberherr et al. 2005 ). The PA L gene is an important defense gene
and the PAL enzyme represents the entry point of phenylpropanoid pathway for the
synthesis of phenolics, phytoalexins, lignins (Vidhyasekaran 2007 ).

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