Clone‐specific responses in leaf phenolics of willows exposed to enhanced UVB radiation and drought stress

Abstract

The effects of enhanced UVB radiation and drought stress on willow secondary phenolics were studied using the leaves of 8-week-old micropropagated plantlets from interspecific hybrids (Salix myrsinites L. Â S. myrsinifolia Salisb.) and pure species (S. myrsinifolia). The plantlets were subjected for 4 weeks to two levels of UVB radiation (ambient, enhanced) and two levels of watering (well-watered, drought-stressed) according to a 2 Â 2 factorial design. Enhanced UVB radiation increased the total concentration of flavonoids and phenolic acids in all plantlets, while the total concentration of salicylates remained unaffected. Drought stress reduced the total concentration of salicylates and phenolic acids in S. myrsinifolia plantlets, while in hybrids only phenolic acids were affected. The response of phenolic acids to enhanced UVB in drought-stressed plantlets was different from that in well-watered ones, indicating that drought stress limited the accumulation of phenolic acids under enhanced UVB radiation. Flavonoids increased in response to enhanced UVB radiation in drought-stressed plantlets, although drought caused serious physiological stress on growth. There were significant differences between hybrid and S. myrsinifolia plantlets with respect to the composition of phenolics and between families and clones with respect to their concentration. In addition, the response of salicylates, flavonoids and phenolic acids to enhanced UVB and drought stress was clone-specific, which may indicate that climatic changes will alter the genetic composition of northern forests.

The Wound-, Pathogen-, and Ultraviolet B-ResponsiveMYB134Gene Encodes an R2R3 MYB Transcription Factor That Regulates Proanthocyanidin Synthesis in Poplar

“…The activation of flavonol biosynthetic genes exhibited a reduction at 12 h, which may have been caused by the absence of the stimulus during the night or by circadian regulation. Flavonol glycosides are known to be important UV-B protective compounds (Li et al, 1993;Landry et al, 1995), and increased flavonol accumulation in leaves has been observed in poplar and other trees under elevated UV-B light (Warren et al, 2002(Warren et al, , 2003Keski-Saari et al, 2005;Turtola et al, 2005). HPLC analysis of extracts from leaves after 7 d of HL exposure revealed a large increase in total flavonol glycosides ( Fig.…”

Herbivores and variation in the composition of specific phenolics of boreal coniferous trees: a search for patterns

“…to exclude the possibility of changes in plant chemical composition due to induced defence (Lieutier et al 2003;Stolter et al 2005;Witzell and Martin 2008) and to avoid confounding due to this potential source of variation. To help eliminate additional confounding variables such as varying chemical composition at different tree heights or due to different light regimes (Close and McArthur 2002;Nordengren et al 2003;Turtola et al 2005), samples were taken from the northern side of the trees, at a height of 130 cm, except for the shorter J. communis, for which 7 cm of a top shoot was taken. We only sampled trees between 160 and 220 cm to reduce variation (with the exception of the shorter J. communis, which was sampled if an individual plant was between 60 and 100 cm).…”

Dark‐leaved willow (Salix myrsinifolia) is resistant to three‐factor (elevated CO2, temperature and UV‐B‐radiation) climate change

“…Previous short‐time studies including one or two climate change factors, report considerable changes in growth and in concentrations of phenolic metabolites in dark‐leaved willow (Julkunen‐Tiitto et al. , 1993; Tegelberg & Julkunen‐Tiitto, 2001; Turtola et al. , 2005, 2006).…”