Accumulation of photosynthetic pigments in Larix decidua Mill. and Picea abies (L.) Karst. cotyledons treated with 5-aminolevulinic acid under different irradiation

Abstract

European larch (Larix decidua Mill.) and Norway spruce [Picea abies (L.) Karst.] synthesize chlorophyll (Chl) in darkness. This paper compares Chl accumulation in 14-d-old dark-grown seedlings of L. decidua and P. abies after shortterm (24 h) feeding with 5-aminolevulinic acid (ALA). We used two ALA concentrations (1 and 10 mM) fed to cotyledons of both species in darkness and in continuous light. The dark-grown seedlings of L. decidua accumulated Chl only in trace amounts and the seedlings remained etiolated. In contrast, P. abies seedlings grown in darkness were green and had significantly higher Chl content. After ALA feeding, higher protochlorophyllide (Pchlide) content was observed in L. decidua than in P. abies cotyledons incubated in darkness. Although short-term ALA feeding stimulated the synthesis of Pchlide, Chl content did not change significantly in cotyledons incubated in darkness. The Chl accumulation in cotyledons fed with ALA was similar to the rate of Chl accumulation in the controls. Higher Chl accumulation was reported in control samples after illumination: 86.9% in L. decidua cotyledons and 46.4% in P. abies cotyledons. The Chl content decreased and bleaching occurred in cotyledons incubated with ALA in light due to photooxidation. Analyses of Chlbinding proteins (D1 and LHCIIb) by Western blotting proved differences between Chl biosynthesis in L. decidua and P. abies seedlings in the dark and in the light. No remarkable increase was found in protein accumulation (D1 and LHCIIb) after ALA application. Our results showed interspecific difference in Chl synthesis between two gymnosperms. Shortterm ALA feeding did not stimulate Chl synthesis, thus ALA synthesis was not the rate-limiting step in Chl synthesis in the dark.

Influence of exogenous 5-aminolevulinic acid on chlorophyll synthesis and related gene expression in oilseed rape de-etiolated cotyledons under water-deficit stress

“…High concentration of ALA (10-20 mM) also had negative effects on Chl accumulation in etiolated leaves of gymnosperms, such as Larix decidua Mill. and Picea abies (L.) Karst, after illumination (Pavlovič et al 2009, Maximová andSlováková 2014). These results suggested that exogenous ALA acted as a growth regulator on Chl content in plants at low concentrations (Hotta et al 1997, Liu et al 2011.…”