H+-Coupled sugar transporter, an initiator of sugar-induced Ca2+-signaling in plant cells.
Using Ca2+-dependent photoprotein aequorin-transformed tobacco BY-2 cell suspensions, the sugar-induced increase in cytosolic free Ca2+ concentration ([Ca2+]cyt) was investigated by measuring the luminescence intensity. When 0.5 M sucrose or some other sugars were fed to the cells, strong and transient luminescence was observed. Salts or sugar analogues didn't show this effect. In addition, the intensity of sucrose-induced aequorin luminescence was gradually enhanced when cells were exposed to sugar-starvation. This was observed with the concurrent expression of the sucrose/H+ co-transporter, NtSUT1A. The [Ca2+]cyt increase may initiate Ca2+-signaling leading to the expression of genes related to biosynthesis of storage carbohydrates in a sink organ. The sugar-signaling may play an important role in the conversion on nutritional stage of plant tissue, source organ to sink organ.
Furuichi
Takuya
T
Graduate School of Medicine, Nagoya University, Showa-ku, Japan. furuichi@med.nagoya-u.ac.jp
Muto
Shoshi
S
D000331:Aequorin / Q000032:analysis; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017930:Genes, Reporter; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051247:Sodium-Glucose Transport Proteins / Q000502:physiology*; D027981:Symporters; D014026:Nicotiana / Q000502:physiology*
D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D051247:Sodium-Glucose Transport Proteins; D027981:Symporters; C089820:monosaccharide-hydrogen cotransporter; D000331:Aequorin; D002118:Calcium