PECT1, a rate-limiting enzyme in phosphatidylethanolamine biosynthesis, is involved in the regulation of stomatal movement in Arabidopsis.
Juntaro NegiTomoki ObataSakura NishimuraBoseok SongSho YamagakiYuhei OnoMakoto OkabeNatsumi HoshinoKohei FukatsuRyo TabataKatsushi YamaguchiShuji ShigenobuMasashi YamadaMitsuyasu HasebeShinichiro SawaToshinori KinoshitaIkuo NishidaKoh IbaPublished in: The Plant journal : for cell and molecular biology (2023)
An Arabidopsis mutant displaying impaired stomatal responses to CO 2 , cdi4, was isolated by a leaf thermal imaging screening. The mutated gene PECT1 encodes CTP:phosphorylethanolamine (PE) cytidylyltransferase. The cdi4 exhibited a decrease in PE levels and a defect in light-induced stomatal opening as well as low CO 2 -induced stomatal opening. We created RNAi lines in which PECT1 was specifically repressed in guard cells. These lines are impaired in their stomatal responses to low CO 2 concentrations or light. Fungal toxin fusicoccin (FC) promotes stomatal opening by activating plasma membrane H + -ATPases in guard cells via phosphorylation. Arabidopsis H + -ATPase1 (AHA1) has been reported to be highly expressed in guard cells and its activation by FC induces stomatal opening. The cdi4 and PECT1 RNAi lines displayed a reduced stomatal opening response to FC. However, similar to in the wild type, cdi4 maintained normal levels of phosphorylation and activation of the stomatal H + -ATPases after FC treatment. Furthermore, the cdi4 displayed normal localization of GFP-AHA1 fusion protein and normal levels of AHA1 transcripts. Based on these results, we discuss how PECT1 could regulate CO 2 - and light-induced stomatal movements in guard cells in a manner that is independent and downstream of the activation of H + -ATPases.