Accumulation of selected phenolics and expression of PAL genes in carrots differing in their susceptibility to carrot fly (Psila rosae F.)

Abstract

Three research problems were addressed in this work: an extent of root damage caused by carrot fly (Psila rosae) in a collection of carrot breeding accessions as well as correlation between resistance to this pest and accumulation of certain phenolics and mRNAs of the genes coding for phenylalanine ammonia-lyase (PAL). Differences in susceptibility between the studied accessions were statistically significant. The most resistant were lines 7262A and DC 96367. Moreover, no correlation was observed between accumulation of the specific metabolites and the extent of the root damage. However, proportion of certain phenolics exhibited positive correlation with the resistant phenotype. This was shown for the ratios of luteolin 7-O-glucoside to kaempferol 3-O-glucoside and methyluteolin 7-O-glucoside to kaempferol 3-O-glucoside. Susceptibility of roots to larval damage also correlated with semi-quantitatively estimated accumulation of PAL1 and PAL3 mRNAs in leaves. Both PAL genes were expressed at the highest level in line DC 96367 and less strongly in line 7262A. Distinctly lower accumulation of the PAL transcripts was observed for the susceptible varieties: Dolanka and Karotan. © 2012 The Author(s).