Caffeic Acid and α-Chaconine Influence the Resistance of Potato Tuber to Phthorimaea operculella (Lepidoptera: Gelechiidae)

Host plant quality can influence insect larval performance and subsequent adult fitness. Advanced hybrid potato clones (donor species: Solanum berthaultii Hawkes) and their parents were evaluated for resistance to the potato tuber moth (PTM) and examined for several biochemical, molecular and physical traits in order to investigate the mechanisms which underlie PTM-resistance. Resistant parent recorded 57% of mortality of pupae in comparison to the 23% observed in the susceptible parent. Expression patterns of specific genes involved in the phenolic biosynthetic pathway show that hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and cinnamate-4-hydroxylase (C4H) reflect chlorogenic and caffeic acid levels in the skin of all the genotypes (0.7 ≤ r ≤ 1.0). Skin α-chaconine and skin caffeic acid strongly and significantly related with PTM larval mortality (r2 = 0.99 and r = 0.90, respectively). This study suggests that skin α-chaconine and skin caffeic acid could play a defensive role against PTM and proposes a PTM resistant clone with high level of these bio-compounds, useful in breeding projects for plant defense and nutritional value purposes.