Variation in leaf phenolics of field‐cultivated willow (Salix myrsinifolia) clones in relation to occurrence of Melampsora rust

Abstract

Summary Concentrations of potential antifungal phenolics in field‐cultivated willow (Salix myrsinifolia) clones were analysed during three growing seasons, and correlated to the occurrence of Melampsora rust. Consistent relationships between phenolics and rust were not found across the experimental years. There was significant clonal and temporal variation in phenolic content and rust frequency. Levels of some phenolics varied considerably within a sequence of four full‐grown leaves, but the variation in rust occurrence within the same leaf sequence was nonsignificant. The results suggest that the possible association between willow phenolics and rusts is not straightforward, and emphasize the importance of long‐term studies to investigate the chemical basis of willow rust interactions.

Phenolic metabolites in the resistance of northern forest trees to pathogens — past experiences and future prospects

“…(+)-Catechin is a building block of condensed tannins, which have been found to correlate negatively with the frequency of Melampsora amygdalina rust on clones of Salix triandra, a willow species that is characterized by high constitutive concentration of condensed tannins (Hjältén et al 2007a; see also the section Induced phenolics for information about induction of catechin in willows). In a 3 year field study, however, the association between concentration of (+)-catechin (or other phenolics) and rust frequency in Salix myrsinifolia clones was not evident (Hakulinen and Julkunen-Tiitto 2000). Varying relationships have also been found between other pathogens and phenolics of northern deciduous trees.…”

“…For instance, one study reported accumulations of benzoic acid in trembling aspen trees bearing black stem galls (Pausler et al 1995), but the compound's role in resistance to Phellinus tremulae heartwood rot remained unclear. In willows, leaf rusts induced changes in (+)-catechin metabolism (Hakulinen and Julkunen-Tiitto 2000), suggesting a mechanistic relationship between (+)-catechin and rust infection (Hakulinen et al 1999). One such mechanism could be related to the role of (+)-catechin as a precursor of condensed tannins, for which antimicrobial activity via protein precipitation and iron depletion has been suggested (Scalbert 1991).…”

“…In some cases, the concentration of phenolics has been found to be highest in young tissues and plant parts, whereas in others opposite trends have been reported (Hakulinen and Julkunen-Tiitto 2000;Johnson and Kim 2005). A strong ontogeny effect on phenolic metabolism has also been observed in the hybrid Populus trichocarpa  Populus deltoides (Johnson and Kim 2005).…”

Variations in total phenolics during ontogenetic, morphogenetic, and diurnal cycles inHypericum species from Turkey

“…Here, we determined that, although the total phenolics content in whole plants at various phenological stages differed significantly among our three Hypencum species, the highest levels were accumulated during the development and opening of the floral buds. Leaves and flowers generally contain greater amounts of phenolic acids and terpenoids than do the stems and roots (Hakulinen and Julkunen-Tiitto, 2000). Moreover, Osinska and Weglarz (2003) have found that flavonoid and hypericin contents in 11 Polish Hypericum species differ significantly, and according to the developmental stage.…”

Relationship between field resistance to Phytophthora ramorum and constitutive phenolic chemistry of coast live oak

“…The role of certain phenolics (both constitutive and induced) in tree defence strategies is well documented, particularly in conifers (Brignolas et al 1998;Schultz and Nicholas 2000;Bonello and Blodgett 2003;Lieutier et al 2003;Venalainen et al 2003;Wallis et al 2008), but also in a few angiospermous species (Bucciarelli et al 1999;Hakulinen et al 1999;Hakulinen and Julkunen-Tiitto 2000;Ruuhola et al 2007;Witzell and Martin 2008). However, few studies have dealt with the defensive role of phenolics against pathogens in stem tissues of oaks.…”