Enhanced UV‐B radiation under field conditions increases anthocyanin and reduces the risk of photoinhibition but does not affect growth in the carnivorous plant Pinguicula vulgaris

Abstract

The effects of enhanced UV-B radiation were investigated in the carnivorous plant Pinguicula vulgaris in a field experiment performed in Abisko, North Sweden (68m 21h N, 18m 49h E, 380 m above sea level). Potted plants were exposed to either ambient or ambient plus supplemental UV-B radiation, simulating a 15% ozone depletion. No effect was observed on either the epicuticular (external) or cellular (internal) UV absorbing capacity of the leaves. However, the anthocyanin content was more than doubled by supplemental UV-B radiation. In laboratory experiments, the anthocyanin rich, UV-B treated leaves were less susceptible to a low temperature\high light photoinhibitory treatment, as judged by in vivo chlorophyll fluorescence measurements. Yet, this potential benefit did not considerably affect the growth of the plant in the field (leaf area and dry mass, reproductive dry mass, flowering frequency, senescence rates, dry mass of winter buds). However, there was a marginally significant increase in root dry mass and in the root to shoot ratio, which may underlie the significant increase in the nitrogen content of the leaves. We suggest that P. vulgaris is resistant against UV-B radiation damage and that the possible negative effects of additional UV-B radiation on the growth of these plants may have been effectively counterbalanced by the lower risk of photoinhibition, due to the concomitant increase in anthocyanins.

Role of Anthocyanins in Plant Defence

“…Sticky exudates from those hairs attract, ensnare, suffocate, and eventually digest small insects. The red pigments, a mix of anthocyanins (Ichiishi et al 1999), clearly did not evolve in this species to repel insects; they may function to attract prey, but a physiological role is just as likely, as has been postulated for anthocyanins in other carnivorous plants (Moran and Moran 1998;Mendez et al 1999). The existence of exceptions does not, of course, vitiate hypotheses for defensive functions of anthocyanins in other red-leafed species.…”

Plastic responses to temporal variation in moisture availability: consequences for water use efficiency and plant performance

“…The production of anthocyanin in leaves was probably not beneWcial, because anthocyanin had either a negative eVect or no eVect on plant size. This suggests that anthocyanin may be indicative of stress (Lee and Lowry 1980;Mendez et al 1999) or cellular damage (Close and Beadle 2003) in the P. caroliniana complex and may not have a high production cost. However, it is also possible that the production of anthocyanin is reducing some other unknown physiological stress (reviewed in Gould 2004).…”

“…SpeciWcally, we examine the expression and plastic responses of a number of leaf traits including leaf area, shape (width/length ratio), trichome density, reXectance, and anthocyanin content during relatively wet and dry periods of the growth season. We estimated anthocyanin because hybrids vary in widely in their pigmentation (Picotte 2006) and anthocyanins protect the leaf by enhancing photo-chemical quenching of highenergy electrons that may damage cells and reduce the photosynthetic rate (Close et al 2000;Mendez et al 1999). We were particularly interested in the eVects of leaf morphological traits on WUE, measured here with C isotope ratio ( 13 C).…”

Association of red coloration with senescence of sugar maple leaves in autumn

“…However, exposure to an array of stressors, including UV-B radiation (Mendez et al 1999), osmotic stress (Kaliamoorthy and Rao 1994), drought (Balakumar et al 1993), low temperatures (Krol et al 1995), nutrient deficiencies (Rajendran et al 1992), wounding (Ferreres et al 1997), pathogen infection (Dixon et al 1994), and ozone exposure (Foot et al 1996) have been shown to elicit anthocyanin biosynthesis. This buildup of anthocyanins following stress exposure raises the possibility that anthocyanins may function, in part, to prevent or offset stressinduced damage.…”