Mild reductions in guard cell sucrose synthase 2 expression leads to slower stomatal opening and decreased whole plant transpiration in Nicotiana tabacum L

• Published in: Environmental and experimental botany 2021-04, Vol.184, p.104370, Article 104370
• Main Authors: Freire, Francisco Bruno S., Bastos, Ricardo L.G., Bret, Raissa S.C., Cândido-Sobrinho, Silvio A., Medeiros, David B., Antunes, Werner C., Fernie, Alisdair R., Daloso, Danilo M.
• Format: Article
• Language: English
• Subjects: Guard cell metabolism; Metabolic network; Plant metabolic engineering; Stomata; Stomatal speediness
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/j.envexpbot.2020.104370

•NtSUS2-silenced plants have slower light-induced stomatal opening.•NtSUS2-silenced plants have a strong reduction in whole plant transpiration.•NtSUS2 silencing altered guard cell metabolic network.•NtSUS2 silencing reduce the accumulation of metabolites positively correlated with stomatal speediness.•The transgenic lines have higher effective use of water under short water deficit periods. 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.