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Plant Cell. 2019 Jun;31(6):1328-1343. doi: 10.1105/tpc.18.00736. Epub 2019 Apr 17.

A Subsidiary Cell-Localized Glucose Transporter Promotes Stomatal Conductance and Photosynthesis.

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Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China
Agro-biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, P.R. China.
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R. China.
Department of Plant Biology, School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
Max-Planck-Institute of Molecular Plant Physiology, Am Muhlenberg 1, Potsdam-Golm 14476, Germany.
National Engineering Laboratory of Crop Stress Resistance Breeding, Anhui Agricultural University, Hefei 230036, P.R. China.
School of Environmental & Life Sciences, The University of Newcastle, Callaghan NSW 2308, Australia.


It has long been recognized that stomatal movement modulates CO2 availability and as a consequence the photosynthetic rate of plants, and that this process is feedback-regulated by photoassimilates. However, the genetic components and mechanisms underlying this regulatory loop remain poorly understood, especially in monocot crop species. Here, we report the cloning and functional characterization of a maize (Zea mays) mutant named closed stomata1 (cst1). Map-based cloning of cst1 followed by confirmation with the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR associated protein 9 system identified the causal mutation in a Clade I Sugars Will Eventually be Exported Transporters (SWEET) family gene, which leads to the E81K mutation in the CST1 protein. CST1 encodes a functional glucose transporter expressed in subsidiary cells, and the E81K mutation strongly impairs the oligomerization and glucose transporter activity of CST1. Mutation of CST1 results in reduced stomatal opening, carbon starvation, and early senescence in leaves, suggesting that CST1 functions as a positive regulator of stomatal opening. Moreover, CST1 expression is induced by carbon starvation and suppressed by photoassimilate accumulation. Our study thus defines CST1 as a missing link in the feedback-regulation of stomatal movement and photosynthesis by photoassimilates in maize.

[Available on 2020-06-01]

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