1. Mesophyll conductance decreases in the wild type but not in an ABA-deficient mutant ( aba1) of N icotiana plumbaginifolia under drought conditions.
- Author
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MIZOKAMI, YUSUKE, NOGUCHI, KO, KOJIMA, MIKIKO, SAKAKIBARA, HITOSHI, and TERASHIMA, ICHIRO
- Subjects
MESOPHYLL tissue ,ELECTRIC admittance ,ABSCISIC acid ,PLANT mutation ,NICOTIANA plumbaginifolia ,EFFECT of drought on plants - Abstract
Under drought conditions, leaf photosynthesis is limited by the supply of CO
2 . Drought induces production of abscisic acid ( ABA), and ABA decreases stomatal conductance ( gs ). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance ( gm ). However, the relationships between ABA content and gm are unclear. We investigated the responses of gm to the leaf ABA content [( ABA)L ] using an ABA-deficient mutant, aba1, and the wild type ( WT) of N icotiana plumbaginifolia. We also measured leaf water potential ( ΨL ) because leaf hydraulics may be related to gm . Under drought conditions, gm decreased with the increase in ( ABA)L in WT, whereas both ( ABA)L and gm were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gm in both WT and aba1 in a dose-dependent manner. ΨL in WT was decreased by the drought treatment to −0.7 MPa, whereas ΨL in aba1 was around −0.8 MPa even under the well-watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in ( ABA)L is crucial for the decrease in gm under drought conditions. We discuss possible relationships between the decrease in gm and changes in the leaf hydraulics. [ABSTRACT FROM AUTHOR]- Published
- 2015
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