Phenolic Responses of Resistant and Susceptible Olive Cultivars Induced by Defoliating and Nondefoliating Verticillium dahliae Pathotypes

Abstract

Verticillium wilt is the most serious olive disease worldwide. The olive-infecting Verticillium dahliae pathotypes have been classified as defoliating (D) and nondefoliating (ND), and the disease is mainly controlled in olive orchards by using resistant or tolerant cultivars. Limited information is available about the nature of resistance in most of the olive cultivars. In the present study, the phenolic responses of the susceptible to V. dahliae olive cv. Amfissis and the resistant cv. Koroneiki upon D and ND V. dahliae infection were monitored in relation to the fungal DNA levels in the vascular tissues with the purpose to explore the defense mechanisms of olive trees against V. dahliae. Quantitative polymerase chain reaction revealed that the decrease in symptom severity shown in Koroneiki trees was associated with significant reduction in the growth of both V. dahliae pathotypes in the vascular tissues compared with Amfissis. In Koroneiki trees, the levels of o-diphenols and verbascoside were positively associated with the DNA levels of the D and ND pathotypes. In addition, a positive association was observed between the levels of verbascoside and the fungal DNA level in Amfissis trees, whereas a negative association was revealed between the fungal DNA level and the total phenols and oleuropein content in both cultivars. The levels of verbascoside were clearly higher in Koroneiki trees compared with Amfissis trees, indicating for the first time in the literature the involvement of verbascoside in the defense mechanism of olive trees against V. dahliae.

Verticillium wilt of olive: a case study to implement an integrated strategy to control a soil-borne pathogen

“…However, little is known on mechanisms responsible of the wilting syndrome or on host defense responses in olive upon V. dahliae infection with the exception of those reported by Baídez et al (2007) and by Markakis et al (2010). Nevertheless, physiological alterations as a consequence of pathogen invasion may have a strong influence on photosynthesis, nutrient translocation, water transport, and/or respiration as described in other hosts (Abeles et al 1992;Resende et al 1996;Sadras et al 2000).…”

“…quercetin, luteolin or rutin) present in olive were suggested to act as phytoanticipins and/or phytoalexins of olive's natural defense or resistance mechanisms (Baídez et al 2007). Recently, Markakis et al (2010) have reported the involvement of verbascoside in defense mechanisms of Greek olive cultivars against V. dahliae.…”

Phenolic profiles in apple leaves and the efficacy of selected phenols against fire blight (Erwinia amylovora)

“…For example, some phenolic derivatives can react with pathogen proteins, causing loss of their enzymatic functions thus suppressing pathogen viability (Markakis et al 2010). The flavonoids were described as having antibacterial, antitoxin, antiviral and/or antifungal activities and as being involved in structural defense (Treutter 2005).…”

Susceptibility of Cultivars to Biotic Stresses

“…Very little is known about biochemical and molecular mechanisms of olive resistance to the Verticillium wilt. Among investigated aspects, it seems to be very important the role of phenolic methabolism (Baidez et al, 2007;Markakis et al, 2010). Vizzarri et al (2011) investigated the susceptibility of cvs.…”

“…Koroneiki showed higher increasing of phenols than susceptible cv. Amfissis when inoculated with verticillium wilt (Markakis et al, 2010). Genes PAL e CHS play an important role in the biosynthesis of phenolic compounds, then a role in determing resistance of olive cultivars to verticillium wilt could be hypothesised.…”