Chlorophyll a fluorescence and phytochemical response in blackberry species (Rubus sp) cultivated in the high tropics

Abstract

BACKGROUND: The evaluation of chlorophyll fluorescence activity is a useful tool for rapid and effective assessments of the effect of abiotic factors on the physiology of different crops. In Rubus, this type of measurements describes tolerance to high temperatures, sensitivity to heat and morphological alterations in flowering and chlorophyll content, as a result of plant stress. OBJECTIVE: The present research estimated chlorophyll fluorescence and the presence of some phenolic compounds in the leaves of three cultivars of blackberry (Rubus sp.) established in the central region of Colombia, under conditions of open air between 2400 and 2800 masl. MATERIAL AND METHODS: This was done through the measurement of chlorophyll a (Junior-PAM II modulated fluorometer), the quantification of phenolic compounds (Folin Ciocalteu), the determination of antioxidant capacity (DPPH and ABTS) and the study of phenolic profiles (UHPLC) in leaves of three blackberry cultivars. RESULTS: Cultivars R. alutaceus (0.66), R. glaucus (0.73) and R. alpinus (0.76), presented values lower than the optimum (0.83), for the parameter Fv/Fm. In addition, the direct relationships between the parameters that define the behavior of PSII and the accumulation of different polyphenols were described. Reference was also made to the content of phenolic compounds (ranging from 125 to 150 mg GA g–1 dw), which did not show significant statistical differences. The heat map and principal component analysis show the close relationship between the parameters that characterize the functioning of PSII and the accumulation of phenolic compounds, as a mechanism of adaptation to the adverse conditions of the blackberry cultivars studied. CONCLUSIONS: The results reveal that the leaves of the Rubus studied could be a source of functional ingredients for use in the cosmetic, nutraceutical and food industries and epigallocatechin was attributed the greatest responsibility for the antioxidant capacity.