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Seasonal variations in UV‐absorbing compounds and physiological characteristics in the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia over a 3‐year period
Author(s) -
NúñezOlivera Encarnación,
Otero Saúl,
Tomás Rafael,
MartínezAbaigar Javier
Publication year - 2009
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2009.01215.x
Subject(s) - seasonality , absorbance , latitude , environmental chemistry , botany , hydroxycinnamic acid , chemistry , ozone , ultraviolet radiation , biology , ecology , antioxidant , biochemistry , chromatography , organic chemistry , geography , geodesy , radiochemistry
Temporal physiological variations in relation to environmental factors, in particular to ultraviolet (UV) radiation, have been studied in bryophytes from circumpolar latitudes, but not in mid‐latitudes with longer growing seasons. In addition, seasonal and interannual changes in individual UV‐absorbing compounds (UVAC) have not been previously studied in bryophytes. To fill these gaps, samples of the aquatic liverwort Jungermannia exsertifolia subsp. cordifolia were collected on a monthly basis during 3 years from a mountain stream in northern Spain. Sclerophylly index, chlorophyll fluorescence, DNA damage, the bulk UV absorbance of methanolic extracts and the concentration of five UVAC (hydroxycinnamic acid derivatives) were measured. Interannual changes were little marked, probably because the 3 years studied were environmentally similar. In summer‐autumn, with respect to seasonal variations, newly grown tender young shoots with high F v /F m accumulated higher amounts of several hydroxycinnamic acid derivatives than in winter‐spring. DNA damage was not detected in any of the samples analyzed. p ‐Coumaroylmalic acid was the compound best associated with radiation changes, and the best model explaining UV‐B took into consideration the concentration of this compound and the ozone level. The specific effects of UV radiation could not be separated from the effects caused by other environmental factors, such as global radiation or temperature, because all these variables were correlated. However, indirect evidence strongly suggests that seasonal changes in bulk UV absorbance and p ‐coumaroylmalic acid are mainly driven by UV radiation. This compound may be a promising physiological variable to be used for UV bioindication.