Poster: Environmental physiology

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Abs # P01010: Adaptations of cellular compartmentation, gene-expression profiles and multiple metabolic pathways in response to sucrose starvation in rice suspension cells

Presenter:	Wang, Huei-Jing       Contact Presenter
Authors	Wang, Huei-Jing  (B) (A)  Hsu, Chia-Mei  (A)   Lee, Kuo-Wei  (C)   Yu, Su-May  (C)   Jauh, Guang-Yuh  (A)
Affiliations:	(A): Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan (B): Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan (C): Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan

Sugar plays an important role for energy generation, cellular architectural construction, and developmental regulation in plants, and sucrose (Suc) starvation causes great changes in cellular morphology, enzyme activities and gene expression. In this study, the cellular and transcriptomic modifications in rice suspension cells (Oryza sativa cv tainung 67) undergoing Suc depletion were investigated via ultra-structural study and genome-wide gene expression profiling. Sequential intermediates of remarkable autophagy-like compartments were found in 2-hr Suc-starved cells, then the expression of genes was induced for several tonoplast proteins and vacuolar proteases. Agilent rice gene chips were used for time-course monitoring of gene expression profiles; 2069 up- and 1686 downregulated genes induced by Suc starvation were identified and incorporated into multiple metabolic pathways. Almost all of the genes encoding enzymes involved in biosynthetic pathways for macromolecules are significantly downregulated, but those involved in the catabolic pathways to degrade macromolecules and sucrose are comprehensively up-regulated. In addition, members of more than a dozen transcription factor families were significantly upregulated under Suc starvation, including bZIP, NAC and MYB. Analyzing the promoter regions of most Suc-starved upregulated genes revealed the presence of several remarkable cis-elements corresponding to the core binding sites for these transcription factors, including the ABA-responsive element (ABRE, ACGTG), coupling element 3 (CE3, CGCGTC), CACG and modified CTTATCC sequences. From above data, we propose sequential cellular and molecular modifications induced by Suc depletion.