Transcript inhibition from limited starch degradation

In starchless mutants of Arabidopsis, pgm, and wild type, Col0, there are small differences in transcript levels at the end of the day, but large differences at the end of the night. Many of the transcripts of genes involved in biosynthesis and growth are repressed in the pgm mutant (Thimm et al., 2004). It is hypothesized that a transient depletion in sugars at the end of the night inhibits carbon utilization at the beginning of the day (Gibon et al., 2004). In order to test if the same inhibition of transcripts involved in biosynthesis and growth also occurs in starch excess mutants of Arabidopsis, Affymetrix arrays will be generated for WT (Col0), and the following mutants: sex4-3 (Salk 102567), ptpkis2 (Salk 053285), and sex1-3 (Yu et al., 2001). WT, sex4-3, and ptpkis2 plants were grown for 30 days and sex1-3 plants were grown for 36 days. All plants were grown in a growth chamber with a 12 hour photoperiod, quantum flux 100 mol m-2s-1, relative humidity was at least 75%, and a constant temperature of 20oC. Three leaves from 8 different plants of each genotype were harvested using a green safe lamp 0.5 hours before the lights came on in the morning and immediately frozen in LN2. Leaf material was powered using a mortar and pestle and RNA was extracted using a Purescript RNA isolation kit (Gentra Systems, MN, USA). Samples were then treated with DNaseI (Invitrogen, CA, USA). 12 samples were used in this experiment.