Photosynthesis and water relations in tomato plants cultivated long-term in media containing (+)-usnic acid.
The influence of (+)-usnic acid on rates of gas exchange (photosynthesis, respiration, and transpiration) in long-term cultivation of tomato plants was studied. The effect was dose-dependent. Plants grown in media containing the maximum concentration of (+)-usnic acid (30 muM) had photosynthetic and respiration rates reduced by 41% and 80%, respectively. The effect on photosynthesis rate may be the result of a multidirectional effect at various stages of this process, which at the highest usnic acid concentration underwent reduction: content of chlorophylls by 30%, carotenoids by 35%, and Hill reaction activity by 75%. Usnic acid also raises the susceptibility of chlorophyll to photodegradation. Under some conditions, transpiration was reduced by 2.1-fold in light and 3.7-fold in dark. This result was correlated with (1) an increase in the diffusive resistance of the stomata (3.1-fold in upper and 1.5-fold in lower surface of leaf), (2) a reduction of stomata density (by 60% on upper and 40% on lower surface), and (3) a 12.3-fold decrease in root hydraulic conductance.
Latkowska
E
E
Department of Plant Physiology and Development, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland.
Lechowski
Z
Z
Bialczyk
J
J
Pilarski
J
J
D001572:Benzofurans / Q000494:pharmacology*; D002338:Carotenoids / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D005740:Gases / Q000378:metabolism; D008027:Light; D018551:Solanum lycopersicum / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D010788:Photosynthesis / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D018515:Plant Leaves / Q000254:growth & development; D018526:Plant Transpiration; D014867:Water / Q000378:metabolism*
D001572:Benzofurans; D005740:Gases; D014867:Water; C073339:usnic acid; D002734:Chlorophyll; D002338:Carotenoids