Gene expression profiles, phenolics and lignin of Sitka spruce bark and sapwood before and after wounding and inoculation with Heterobasidion annosum

Gene expression levels (PAL, CCR1, HCT1, and CAD for the phenylpropanoid pathway, PX3 peroxidase,and CHI4 class IV chitinase), lignin, and soluble and cell wall bound phenolic compounds in bark andsapwood of
Picea sitchensis
clones inoculated withHeterobasidion annosum s.s.were compared beforeand 3 days after wounding and arti¿cial inoculation, at site of inoculation and 1 cm above the inoculationsite.In bark all genes were up-regulated at the site of inoculation but, except for CAD, not in the distal zone.In sapwood all genes were down-regulated, except for PX3 and CHI4; PAL, CCR1, HCT1 and CAD werepresent at lower levels around the inoculation site than in the distal zone. Compared to wounding only,inoculation withH. annosumtriggered different CAD, PX3, and CHI4 levels in bark but not in sapwood.Different concentrations of cell wall bound phenolic compounds (unknown2, unknown3, coniferin,astringin, taxifolin, piceid, and isorhapontin) were found in bark after wounding and inoculationcompared to constitutive material (i.e. untreated samples), whereas in sapwood concentrations did notdiffer following treatment. These results indicate that bark of Sitka spruce has a stronger and earlierresponse to wounding and pathogen inoculation than sapwood.