Ms. Jimenez et al., ENVIRONMENTAL STRESSES AND ANTIOXIDATIVE RESPONSES OF PINUS-CANARIENSIS AT DIFFERENT FIELD STANDS IN TENERIFE, Phyton, 37(3), 1997, pp. 109-114
In the present paper, we investigate antioxidants, chloroplast pigment
s, ultrastructure, and chlorophyll fluorescence in needles of Pinus ca
nariensis Chr. Sm. ex DC. collected at four natural stands covering an
altitude range from 200 to 2000 m a. s. 1. in the South-East of Tener
ife. The contents of chloroplast pigments were lower at the most eleva
ted sites showing chlorophyll concentrations of about 1 mg g(-1) needl
e dry weight (DW) versus 2 mg g(-1) DW at the lowest sites. Mean antio
xidant concentrations in one year old needles were 260 to 200 mu g g(-
1) DW for alpha-tocopherol, 3 to 4.5 mg (-1) DW for ascorbic acid and
340 to 180 nmol g(-1) DW for glutathione. A strict altitude dependence
of these parameters was not found. Chlorophyll fluorescence measureme
nts revealed Fv/Fm above 0.75 for all sites indicating healthy photosy
nthetic apparatus, but revealed initial states of oxidative stress at
one particular site. Depressions in Fv/Fm went together with decreased
alpha-carotene/beta-carotene ratios and a decrease in the ratio of vi
olaxanthin to total xanthophyll cycle carotenoids. Ultrastructural inv
estigations of the chloroplasts indicated no severe damage to the thyl
akoid systems.