ABSTRACT: Sugar is an important resource for energy generation and developmental regulation in plants, and sucrose starvation causes enormous changes in cellular morphology, enzyme activities and gene expression. Genome-wide gene expression profiling provides a comprehensive knowledge into gene expression under nutrients depletion and senescence, however, that of monocot model plant rice under sucrose depletion is still under investigation. Here, the time-course monitoring of gene expression profiles in sucrose-starved rice (Oryza sativa cv Tainung67) suspension cells was investigated by 21495 probes-containing Agilent rice chip. In sucrose-starved cells, the induced vacuolar biogenesis was coincided with the significantly upregulated expression of genes encoding H+-pyrophosphatase, ï?¤-TIP, one putative ï?¡-TIP, several vacuolar proteases and proteinase inhibitors, and one OsATG3. To survey the overall metabolic adaptations under sucrose depletion the genes significantly alternating expression level were incorporated into multiple metabolic pathways. The majority of genes encoding enzymes involved in biosynthesis and degradation pathways of various macromolecules were comprehensively down- and upregulated, respectively, by sucrose starvation. Transcriptional regulation of gene expression is important for the physiological adaptations to environmental stress and many transcription factors, including bZIPs, NACs, and WRKY showed significant increase in transcript levels under sucrose starvation. Concurrently, statistical analysis reveals that their corresponding consensus cis-elements, such as ABA-responsive element, CACG, ACI, ACII and CTTATCC, are frequently found in the promoter regions of many Suc starvation-upregulated genes. Particle bombardment-mediated transient promoter activity assays further showed that the CTTATCC, derived form TATCCA, and the AC motifs, are the promising sucrose starvation responsive activators in sucrose-starved rice suspension cells. Experiment Overall Design: We used Agilent rice gene chips to investigate the gene expression profiling in rice cells after periods of 12, 24 and 48 h Suc starvation. To eliminate the effect of osmotic stress on alternation of gene expression, an additional set of control, 88 mM Sorbitol in MS medium verse Suc-free samples for 12 h Suc starvation, was also applied for array analysis.
