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Ozone inhibits guard cell K + channels implicated in stomatal opening

1999; National Academy of Sciences; Volume: 96; Issue: 23 Linguagem: Inglês

10.1073/pnas.96.23.13577

1091-6490

Gro Torsethaugen, Eva J. Pell, Sarah M. Assmann,

Atmospheric chemistry and aerosols

Ozone (O 3 ) deleteriously affects organisms ranging from humans to crop plants, yet little is understood regarding the underlying mechanisms. In plants, O 3 decreases CO 2 assimilation, but whether this could result from direct O 3 action on guard cells remained unknown. Potassium flux causes osmotically driven changes in guard cell volume that regulate apertures of associated microscopic pores through which CO 2 is supplied to the photosynthetic mesophyll tissue. We show in Vicia faba that O 3 inhibits ( i ) guard cell K + channels that mediate K + uptake that drives stomatal opening; ( ii ) stomatal opening in isolated epidermes; and ( iii ) stomatal opening in leaves, such that CO 2 assimilation is reduced without direct effects of O 3 on photosynthetic capacity. Direct O 3 effects on guard cells may have ecological and agronomic implications for plant productivity and for response to other environmental stressors including drought.