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

Claudio Inostroza-B., Marjorie Reyes-Díaz, Alejandro Arellano, Mirtha Latsague, Patricio Acevedo A., Rodrigo Loyola, Patricio Arce-Johnson and Miren Alberdi


The effects of increased doses of UV-B radiation on anatomical, biochemical and molecular features of leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes were À2investigated. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 Wm 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 WmÀ2, 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.

DOI: http://dx.doi.org/10.1016/j.plaphy.2014.10.015