Sugar coordinately and differentially regulates growth- and stress-related gene expression via a complex signal transduction network and multiple control mechanisms.
In plants, sugars are required to sustain growth and regulate gene expression. A large set of genes are either up- or down-regulated by sugars; however, whether there is a common mechanism and signal transduction pathway for differential and coordinated sugar regulation remain unclear. In the present study, the rice (Oryza sativa cv Tainan 5) cell culture was used as a model system to address this question. Sucrose and glucose both played dual functions in gene regulation as exemplified by the up-regulation of growth-related genes and down-regulation of stress-related genes. Sugar coordinately but differentially activated or repressed gene expression, and nuclear run-on transcription and mRNA half-life analyses revealed regulation of both the transcription rate and mRNA stability. Although coordinately regulated by sugars, these growth- and stress-related genes were up-regulated or down-regulated through hexokinase-dependent and/or hexokinase-independent pathways. We also found that the sugar signal transduction pathway may overlap the glycolytic pathway for gene repression. alpha-Amylase and the stress-related genes identified in this study were coordinately expressed under sugar starvation, suggesting a convergence of the nutritional and environmental stress signal transduction pathways. Together, our studies provide a new insight into the complex signal transduction network and mechanisms of sugar regulation of growth and stress-related genes in plants.
Ho
S
S
Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan 11529, Republic of China.
Chao
Y
Y
Tong
W
W
Yu
S
S
D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D015723:Gene Library; D012275:Oryza / Q000235:genetics* / Q000254:growth & development*; D010957:Plasmids; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D013395:Sucrose / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
D018076:DNA, Complementary; D012333:RNA, Messenger; D013395:Sucrose