Skip to main content
. 2012 Mar 22;7(3):e33111. doi: 10.1371/journal.pone.0033111

Figure 5. A proposed model to explain how tbz17-ox plant cell accumulates higher sucrose and becomes enlarged.

Figure 5

In WT tobacco cells, when the endogeneous tbz17 gene is transcribed and its transcript contained SC-uORF. The gene product, TBZ17, transactivates NtASN gene and then indirectly activates SPS and SPP genes through metabolic reprogramming, which turns on the sucrose accumulation. If the SC-uORF of tbz17 transcript senses higher sucrose concentration, SIRT is induced, therefore, cellular sucrose concentration is maintained in a certain range. tbz17-ox plant cells (1.5-fold enlarged cell) contain not only the endogenous tbz17 gene but also the transgene `tbz17’ which transcript does not contain SC-uORF. In the latter cells, the gene product TBZ17 directs the transactivation of ASN gene and indirectly upregulates `SPS and SPP’ genes. Increased sucrose concentration represses the translation of endogenous transcript carrying SC-uORF but not the transgene-derived transcript, thus sucrose concentration increased more compared to WT cells. To adjust the high osmotic pressure due to high sucrose concentration, the cell adsorbs more water and become enlarged.