In:
New Phytologist, Wiley, Vol. 132, No. 4 ( 1996-04), p. 641-652
Abstract:
Pormelia sulcata Taylor was used as a model to examine the effects of elevated CO 2 and/or O 3 on green algal lichens. Thalli were exposed for 30 d in duplicate controlled‐environment chambers to two atmospheric concentrations of CO 2 (‘ambient’ [350μmol mol −1 ] and ‘elevated’ [700μmol mol −1 ] 24 h d −1 ) and two O 3 regimes (‘non‐polluted’ air [CF, 〈 5 nmol mol −1 ] and ‘polluted’ air [15 nmol mol −1 overnight rising to a midday maximum of 75 nmol mol −1 ]), in a factorial design. Elevated CO 2 , or elevated O 3 depressed the light saturated rate of CO 2 , assimilation A sat ) measured at ambient CO 2 , by 30% and 18%, respectively. However, despite this effect ultrastructure) studies revealed increased lipid storage in cells of the photobiont in response to CO 2 ‐enrichment. Simultaneous exposure to elevated O 3 reduced CO 2 ‐induced lipid accumulation and reduced A sat in an additive manner. Gold‐antibody labelling revealed that the decline in photosynthetic capacity induced by elevated CO 2 and/or O 3 was accompanied by a parallel decrease in the concentration of Rubiscoa in the algal pyrenoid ( r = 0.93). Interestingly, differences in the amount of Rubisco protein were not correlated with changes in pyrenoid volume. Measurements of in vivo chlorophyll‐fluorescence induction kinetics showed that the decline in A sat induced by elevated CO 2 , and/or O 2 , was not associated with significant changes in the photochemical efficiency of photosystem (PS) II. Although the experimental conditions inevitably imposed some stress on the thalli, revealed as a significant decline in the efficiency of PS II photochemistry, and enhanced starch accumulation in the photobiont over the fornication period, the study shows that the green‐algal lichen symbiosis might be influenced by future changes in atmospheric composition. Photosynthetic capacity, measured at ambient CO 2 , was found to be reduced after a controlled 30 d exposure to elevated CO 2 , and/or O 3 and this effect was associated with a parallel decline in the amount of Rubisco in the pyrenoid of algal chloroplasts.
Type of Medium:
Online Resource
ISSN:
0028-646X
,
1469-8137
DOI:
10.1111/nph.1996.132.issue-4
DOI:
10.1111/j.1469-8137.1996.tb01882.x
Language:
English
Publisher:
Wiley
Publication Date:
1996
detail.hit.zdb_id:
208885-X
detail.hit.zdb_id:
1472194-6
Permalink