Relative expression of seven candidate genes for pathogen resistance on Pinus radiata infected with Fusarium circinatum

• Microdroplet inoculation is a reliable and rapid method for resistant genotype selection.
• Spray inoculation method is a suitable method for infected plants gene expression analysis.
• Suitable housekeeping genes for P. radiata gene expression studies are reported.
• Expression of PR genes (pr5, pr9) increased significantly in the resistant genotypes.
• A higher increase in pcber, pst and pal gene expression was observed in resistant genotypes.

The objective of this research was to assess the relative expression of candidate genes associated to plant disease resistance in Pinus radiata inoculated with Fusarium circinatum by using two different inoculation methods. Microdroplet inoculation allowed an earlier and reliable selection of contrasting genotypes, however, spray inoculation method was more informative for gene expression analysis. Thaumatin-like protein, peroxidase, phenylalanine ammonia lyase, pinosylvin synthase and phenylcoumaran benzylic ether reductase genes increased significantly their transcription levels after inoculation with the pathogen in the resistant genotype, while in the susceptible genotype these genes showed lower relative expression.