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Mesophyll conductance decreases in the wild type but not in an ABA‐deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions
- MIZOKAMI, YUSUKE, NOGUCHI, KO, KOJIMA, MIKIKO, SAKAKIBARA, HITOSHI, TERASHIMA, ICHIRO
- Plant, cell and environment 2015 v.38 no.3 pp. 388-398
- Nicotiana plumbaginifolia, abscisic acid, carbon dioxide, dose response, drought, fluid mechanics, leaf water potential, leaves, mesophyll, mutants, photosynthesis, stomatal conductance, water stress
- Under drought conditions, leaf photosynthesis is limited by the supply of CO₂. 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 gₘare unclear. We investigated the responses of gₘto the leaf ABA content [(ABA)L] using an ABA‐deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (ΨL) because leaf hydraulics may be related to gₘ. Under drought conditions, gₘdecreased with the increase in (ABA)Lin WT, whereas both (ABA)Land gₘwere unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gₘin both WT and aba1 in a dose‐dependent manner. ΨLin WT was decreased by the drought treatment to −0.7 MPa, whereas ΨLin 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)Lis crucial for the decrease in gₘunder drought conditions. We discuss possible relationships between the decrease in gₘand changes in the leaf hydraulics.