Cardoso Amanda A, Brodribb Timothy J, Kane Cade N, DaMatta Fábio M, McAdam Scott A M
School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
AoB Plants. 2020 Jun 19;12(4):plaa025. doi: 10.1093/aobpla/plaa025. eCollection 2020 Aug.
Dynamic variation of the stomatal pore in response to changes in leaf-air vapour pressure difference (VPD) constitutes a critical regulation of daytime gas exchange. The stomatal response to VPD has been associated with both foliage abscisic acid (ABA) and leaf water potential (Ψ ); however, causation remains a matter of debate. Here, we seek to separate hydraulic and hormonal control of stomatal aperture by manipulating the osmotic potential of sunflower leaves. In addition, we test whether stomatal responses to VPD in an ABA-deficient mutant () of sunflower are similar to the wild type. Stomatal apertures during VPD transitions were closely linked with foliage ABA levels in sunflower plants with contrasting osmotic potentials. In addition, we observed that the inability to synthesize ABA at high VPD in plants was associated with no dynamic or steady-state stomatal response to VPD. These results for sunflower are consistent with a hormonal, ABA-mediated stomatal responses to VPD rather than a hydraulic-driven stomatal response to VPD.
气孔孔径随叶-气蒸汽压差（VPD）变化的动态变化构成了白天气体交换的关键调节。气孔对VPD的响应与叶片脱落酸（ABA）和叶水势（Ψ）都有关；然而，因果关系仍存在争议。在这里，我们试图通过操纵向日葵叶片的渗透势来区分气孔孔径的水力控制和激素控制。此外，我们测试了向日葵ABA缺陷突变体（）中气孔对VPD的响应是否与野生型相似。在具有不同渗透势的向日葵植株中，VPD转变期间的气孔孔径与叶片ABA水平密切相关。此外，我们观察到，在高VPD条件下无法合成ABA的植株对VPD没有动态或稳态的气孔响应。向日葵的这些结果与激素介导的、ABA介导的气孔对VPD的响应一致，而不是水力驱动的气孔对VPD的响应。
