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Mild reductions in guard cell sucrose synthase 2 expression leads to slower stomatal opening and decreased whole plant transpiration in tobacco
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  • Francisco Freire,
  • Ricardo Bastos,
  • Raissa Bret,
  • Silvio Cândido‐Sobrinho,
  • David Medeiros,
  • Werner Antunes,
  • Alisdair R. Fernie,
  • Danilo Daloso
Francisco Freire
Universidade Federal do Ceara

Corresponding Author:brunotesaiga@hotmail.com

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Ricardo Bastos
Universidade Federal do Ceara
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Raissa Bret
Universidade Federal do Ceara
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Silvio Cândido‐Sobrinho
Universidade Federal do Ceara
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David Medeiros
Max Planck Institute of Molecular Plant Physiology
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Werner Antunes
Universidade Federal de Viçosa
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Alisdair R. Fernie
Max-Planck Institute for Molecular Plant Physiology
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Danilo Daloso
Universidade Federal do Ceara
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Abstract

The understanding of the dynamics of stomatal movements has increased substantially through genetic manipulation of plant metabolism either at the whole plant level or specifically in guard cells. However, the regulation of stomatal speediness remains not completely elucidated. Here we shown that reduced expression of guard cell sucrose synthase 2 (NtSUS2) of Nicotiana tabacum L. altered the topology and the connectivity of the guard cell metabolic network and the accumulation of metabolites positively correlated with stomatal speediness during dark-to-light transition. This leads to a slower light-induced stomatal opening, lower steady-state stomatal conductance and a strong reduction (up to 44%) in daily whole plant transpiration in the transgenics, when compared to wild type plants. Furthermore, the transgenic lines transpired more or have lower reduction in whole plant transpiration under short water deficit periods, indicating a higher effective use of water under this condition. Our results collectively suggest that the regulation of stomatal movement and speediness involve a complex modulation of the guard cell metabolic network, in which NtSUS2 has an important role. The results are discussed on the role of guard cell metabolism for the regulation of both stomatal speediness and whole plant transpiration.