PHENYLPROPANOID COMPOUNDS IN PRIMARY LEAF TISSUES OF RYE (SECALE-CEREALE) - LIGHT RESPONSE OF THEIR METABOLISM AND THE POSSIBLE ROLE IN UV-B PROTECTION
S. Reuber et al., PHENYLPROPANOID COMPOUNDS IN PRIMARY LEAF TISSUES OF RYE (SECALE-CEREALE) - LIGHT RESPONSE OF THEIR METABOLISM AND THE POSSIBLE ROLE IN UV-B PROTECTION, Physiologia Plantarum, 97(1), 1996, pp. 160-168
The present study was undertaken in order to investigate the suitabili
ty of certain markers for UV plant response. In addition, we attempted
to link the internal tissue distribution of specific UV-absorbing com
pounds to profiles of radiation gradients within intact primary rye le
aves (Secale cereale L. cv. Kustro). Etiolated rye seedlings irradiate
d with low visible light (LL) and/or UV radiation were used to study e
nzyme activities of the two key enzymes, phenylalanine ammonia-lyase (
PAL) and chalcone synthase (CHS), together with the tissue-specific ac
cumulation of soluble phenylpropanoid products. Plants grown under rel
atively high visible light(HL) with or without supplementary UV-B radi
ation were used for further characterization Apparent quantum yield an
d fluorescence quenching parameters were monitored to assess potential
physiological changes due to UV-B exposure in HL-grown seedlings. A q
uartz fibreoptic microprobe was used to characterize the internal UV-B
gradient of the leaf. The response of the phenylpropanoid metabolism
to UV radiation was similar in primary leaves of both etiolated and HL
-treated green plants. The epidermis-specific flavonoids together with
CHS activity turned out to be suitable markers for assessing the effe
ct of UV on the phenolic metabolism. Tile functional role of phenylpro
panoid compounds was strongly implicated in protecting rye from UV-B r
adiation.