The Study On Repression Of Cell Death In Arabidopsis Sscd1 Mutant By Sugar

Sugar not only provides energy and carbon, but also regulates programmed cell death in plants. In previous study, we found that SSCD1 gene encodes an Arabidopsis putative FAH (famarylacetoacetate hydrolase) and the sscdl (short-day sensitive cell death 1) mutant displays cell death under short-day condition, which could be repressed by sucrose. In order to investigate the mechanism of sugar on sscdl cell death suppression, we performed the following studies:1. We conducted an experiment that analyzed the effect of different sugar on sscdl cell death. The results suggested that cell death in sscdl could be also repressed by glucose, fructose, and maltose but not lactose, and this repression is in a dose-dependent manner.2. We analyzed tyrosine degradation pathway related genes expression by the means of real-time quantitative PCR. The results suggested that the occurrence of cell death in sscdl is accompanied by the up-regulation of Tyr degradation pathway genes HGO and MAAI, which could be suppressed by high concentrations of sugar.3. We analyzed cell wall invertase gene cwINV1 expression by the means of real-time quantitative PCR. The results suggested that the cell death in sscdl was accompanied by the up-regulation of cwINVl, which could be repressed by high concentrations of sugar.4. We constructed a plant expression vector of cwINV1 promoter fused with GUS report genes, and then transformed it into Arabidopsis Col-0 and sscdl mutant. GUS stained results showed the correctness and practicability of the recombinant expression vector. In addition, when seedlings were transferred from long day to short day the expression of GUS was significantly induced in the cotyledon of sscdl compared to wild type, but could not be detected in the died true leaves of sscdl, suggesting that the cwINV1 gene is up-regulated in the cotyledon once cell death occurred in the sscdl seedlings.