Improved elongation of Scots pine seedlings under blue light depletion is not dependent on resource acquisition

Abstract

Removal of blue light (400–500 nm) induced shoot elongation of 2-year-old Scots pine (Pinus sylvestris L.) seedlings, which was not related to resource acquisition (carbohydrates, C/N ratio and soluble proteins) and frost hardening. The seedlings were grown in northern Finland (64°N) in plexiglass chambers, either orange in colour or transparent, during elongation and cold hardening periods in 2001. The orange chamber removed the blue wavelengths. The results suggest that the growth inhibiting effect of blue light on Scots pine elongation is probably a photomorphogenic regulation response; the removal of blue light did not affect the gas exchange and accumulation of growth resources. In addition, the removal of blue light also did not affect the physiological parameters (pigment composition, chlorophyll fluorescence and lipid peroxidation) measured during the preparation for winter.

Testing trait plasticity over the range of spectral composition of sunlight in forb species differing in shade tolerance

“…Among physiological traits, there was a distinct decrease in N content in response to the attenuation of blue light, while Chl content only decreased slightly, consistently with the response reported in other field experiments, e.g. in Scots pine (Sarala et al, 2009). Compared with model plants, wild species have adapted a set of traits appropriate for the characteristic spectral regions and/ or other environmental factor defining their habitats (Oguchi et al, 2017;Wang, Kamiyama, Hidema, & Hikosaka, 2016).…”

Antagonistic action of blue and red light on shoot elongation in petunia depends on gibberellin, but the effects on flowering are not generally linked to gibberellin

“…The previously reported lower transcript level of a GA20ox in petunia under R, compared to B light (Fukuda et al, 2012), is consistent with the observed effects of these light qualities on shoot elongation, and suggests a R lightinduced down-regulation in GA level. A high irradiance of B light is effective in suppressing shoot elongation in a range of plant species, including etiolated hypocotyls (Cosgrove, 1981;Wheeler et al, 1991;Honecke et al, 1992;Cosgrove, 1994;Sarala et al, 2009). In contrast to this, in petunia B light enhances elongation of the main stem (Table 1).…”

Species-specific differences in synthesis of flavonoids and phenolic acids under increasing periods of enhanced blue light

“…This result is in accordance with the growth suppressing effect of red light found by Ballare (2014, and references therein), and the conclusion that removal of blue light increased elongation of many species (Sarala et al, 2011). In Scots pine seedlings the observed stem elongation is thought to be a photomorphogenic response, which is not dependent on gas exchange or accumulation of growth resources (Sarala et al, 2009). These reactions may be explained by flavonoids through altered p-coumaroyl CoA metabolism mediating photomorphogenic responses (e.g.…”