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The K + channel KZM 2 is involved in stomatal movement by modulating inward K + currents in maize guard cells
Author(s) -
Gao YongQiang,
Wu WeiHua,
Wang Yi
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13712
Subject(s) - guard cell , shaker , biophysics , transpiration , microbiology and biotechnology , xenopus , ion transporter , ion channel , chemistry , stomatal conductance , biology , photosynthesis , botany , biochemistry , membrane , physics , gene , receptor , quantum mechanics , vibration
Summary Stomata are the major gates in plant leaf that allow water and gas exchange, which is essential for plant transpiration and photosynthesis. Stomatal movement is mainly controlled by the ion channels and transporters in guard cells. In Arabidopsis, the inward Shaker K + channels, such as KAT 1 and KAT 2, are responsible for stomatal opening. However, the characterization of inward K + channels in maize guard cells is limited. In the present study, we identified two KAT 1‐like Shaker K + channels, KZM 2 and KZM 3 , which were highly expressed in maize guard cells. Subcellular analysis indicated that KZM 2 and KZM 3 can localize at the plasma membrane. Electrophysiological characterization in HEK 293 cells revealed that both KZM 2 and KZM 3 were inward K + (K in ) channels, but showing distinct channel kinetics. When expressed in Xenopus oocytes, only KZM 3, but not KZM 2, can mediate inward K + currents. However, KZM 2 can interact with KZM 3 forming heteromeric K in channel. In oocytes, KZM 2 inhibited KZM 3 channel conductance and negatively shifted the voltage dependence of KZM 3. The activation of KZM 2– KZM 3 heteromeric channel became slower than the KZM 3 channel. Patch‐clamping results showed that the inward K + currents of maize guard cells were significantly increased in the KZM 2 RNA i lines. In addition, the RNA i lines exhibited faster stomatal opening after light exposure. In conclusion, the presented results demonstrate that KZM 2 functions as a negative regulator to modulate the K in channels in maize guard cells. KZM 2 and KZM 3 may form heteromeric K in channel and control stomatal opening in maize.