INTRODUCTION Anthocyanins are one of the most widespread classes of pigments in higher plants. They are important sec- ondary metabolites produced through the flavonoid biosynthetic pathway in various plant organs (Winkel- Shirley, 2001). The anthocyanin biosynthetic pathway is controlled by environmental factors (light and tem- perature) and internal factors: plant hormones, other secondary metabolites and nutrients (Mol et al., 1996). Light acts as an essential stimulus and as a factor modulating the intensity of the pigment by affecting the regulatory and structural genes of antho- cyanin biosynthesis. Although photoinduction of anthocyanin has been extensively studied in a variety of plants, the photoreceptors responsible have not been clearly defined (Sheoran et al., 2006). Anthocyanin synthesis involves many steps, from the primary precursor (phenylalanine) to the final products – glycosides of anthocyanidines. Phenylalanine ammonia-lyase (PAL) is the first enzyme to catalyze the elimination of NH 3 from L-phenylalanine to give trans-cinnamate (Hanson and Havir, 1981). Trans-cinnamate can be a precursor of other secondary plant metabolites besides antho- cyanins: phenolic acids, flavonols, lignins, proantho- cyanidines, stilbenes, etc. PAL activity has been reported to positively cor- relate with anthocyanin synthesis in grapes (Kataoka et al., 1983), strawberries (Given et al., 1988) and apples (Tan, 1979), but its role in regulating antho- cyanin formation remains unclear. According to Wang et al. (2000), PAL is not the only factor regulating anthocyanin accumulation in apple fruit; they found that anthocyanin accumulation decreased when apples ripened, even though PAL activity was relative- ly high. Anthocyanins play an important role in attracting insects or animals for pollination and seed dispersal. They also play a role as anti-oxidants and in protect- ing DNA and the photosynthetic apparatus from high radiation fluxes (Gould, 2004). Other possible func- tions of anthocyanins, such as protecting against cold stress or providing drought resistance, are likely to be associated with activities restricted to particular classes of plants (Chalker-Scott, 1999). *e-mail: mhorbowicz@ap.siedlce.pl METHYL JASMONATE INHIBITS ANTHOCYANIN SYNTHESIS IN SEEDLINGS OF COMMON BUCKWHEAT (FAGOPYRUM ESCULENTUM MOENCH) MARCIN HORBOWICZ 1* , ANNA GRZESIUK 1 , HENRYK DĘBSKI 1 , DANUTA KOCZKODAJ 1 AND MARIAN SANIEWSKI 2 1 Department of Plant Physiology and Genetics, University of Podlasie, ul. Prusa 12, 08–110 Siedlce, Poland 2 Research Institute of Pomology and Floriculture, ul. Pomologiczna 18, 96–100 Skierniewice, Poland Received March 31, 2008; revision accepted November 22, 2008 Exogenously applied jasmonic acid methyl ester (JA-Me) inhibited biosynthesis and accumulation of antho- cyanins in hypocotyls of seedlings of etiolated common buckwheat (Fagopyrum esculentum Moench) exposed to light. The phenomenon was observed in experiments with various methods of JA-Me treatment, in whole seedlings and in excised hypocotyls. Even very low quantities of JA-Me taken by seeds during imbibition were enough to inhibit anthocyanin synthesis in buckwheat hypocotyls. This means that there are no significant bar- riers to the transport and action of JA-Me in buckwheat seedlings, as solute and in gaseous form. Although JA-Me inhibited accumulation of anthocyanins in buckwheat hypocotyls, it had no effect on phenylalanine and tyrosine ammonia-lyase activity. Such JA-Me action suggests that it can act not in the first but in later steps of anthocyanin biosynthesis. JA-Me had no effect on the level of anthocyanins in cotyledons or on hypocotyl growth, but clearly inhibited the growth of main roots of buckwheat seedlings. Key words: Anthocyanins, Fagopyrum esculentum, common buckwheat, hypocotyls, cotyledons, methyl jasmonate. PL ISSN 0001-5296 © Polish Academy of Sciences, Cracow 2008 ACTA BIOLOGICA CRACOVIENSIA Series Botanica 50/2: 71–78, 2008