Effects of UV-B radiation on anatomical characteristics, phenolic compounds and gene expression of the phenylpropanoid pathway in highbush blueberry leaves

Inostroza Blancheteau, Claudio
Reyes Diaz, Marjorie
Arellano, Alejandro
Latsague Vidal, Mirtha
Acevedo, Patricio
Loyola, Rodrigo
Arce Johnson, Patricio
Alberdi, Miren
Datos de publicación:
The effects of increased doses of UV-B radiation on anatomical, biochemical and molecular features of leaves of two highbush blueberry (Vaccinium colymbosum L cv. Brigitta and Bluegold) genotypes were investigated. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 Wm(-2) of biologically effective UV-B radiation for up to 72 h. Leaf thickness and the adaxial epidermis thickness fell more than 3-fold in both genotypes at the highest UV-B dose. Moreover, in Bluegold an evident disorganization in the different cell layers was observed at the highest UV-B radiation. A significant decrease in chlorophyll a/b after 6 h in Brigitta under the greater UV-B doses was observed. Anthocyanin and total phenolics were increased, especially at 0.19 Wm(-2), when compared to the control in both genotypes. Chlorogenic acid was the most abundant hydroxycinnamic acid in Brigitta, and was significantly higher (P <= 0.05) than in Bluegold leaves. Regarding the expression of phenylpropanoid genes, only the transcription factor VcMYBPA1 showed a significant and sustained induction at higher doses of UV-B radiation in both genotypes compared to the controls. Thus, the reduction of leaf thickness concomitant with a lower lipid peroxidation and rapid enhancement of secondary metabolites, accompanied by a stable induction of the VcMYBPA1 transcription factor suggest a better performance against UV-B radiation of the Brigitta genotype. (C) 2014 Elsevier Masson SAS. All rights reserved.