The Decay of O3 through Direct Reaction with Cell Wall Ascorbate is not Sufficient to Explain the Different Degrees of O3-sensitivity in two Poplar Clones
1999; Elsevier BV; Volume: 154; Issue: 2 Linguagem: Inglês
10.1016/s0176-1617(99)80216-8
ISSN1618-1328
AutoresAnnamaria Ranieri, Antonella Castagna, E. Padu, Heino Moldau, M. Rahi, Gianfranco Soldatini,
Tópico(s)Plant Stress Responses and Tolerance
ResumoOzone (O3) flux to the mesophyll cell walls and its decay in the direct reaction with cell wall-ascorbate were quantified by measuring stomatal conductance, cell wall ozone-exposed area, cell wall thickness and cell wall-ascorbate concentration in two differently-sensitive poplar clones exposed to O3 (0.150 γl L-1 for 5 h). Stomatal closure under O3 was more pronounced in the sensitive Eridano than in the resistant I-214 poplar clone. The relative internal area in the ozonated sensitive clone was significantly (−21 %) lower than that in the control one. The concentration of reduced ascorbate in the cell wall ([ASAcw]) of the sensitive clone was initially 81 % higher than in the resistant one. Following O3 treatment, [ASAcw] increased more than 3-fold in both clones, while there was a much more rapid increase in dehydroascorbic acid concentration [DHAcw] in the sensitive clone. Calculated ozone flux to mesophyll cell wall and to plasmalemma was compared between the two clones. The decay of O3 flux in cell wall was more rapid in the sensitive clone, due to the more rapid rise of [ASAcw] under O3, but the total (stomatal+cell wall) attenuation of O3 flow during the exposure was similar in both of the clones. It is concluded that the decay of O3 through direct reaction with cell wall ascorbate is not sufficient to explain the different O3-sensitivity in two poplar clones.
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