Effect of myb107 mutation and temperature on seedcoat and endosperm gene expressions during mature green stage
Seed dormancy is an adaptive trait whereby germination is blocked under favourable conditions to avoid germination out of season. Over time mature dry seeds lose dormancy and gradually acquire the capacity to germinate. Dormancy levels, i.e. the time required to release dormancy of the newly produced dry seed, are influenced by the environment of the mother plant and particularly by cold temperatures, which increase dormancy levels. It is also known that the seed coat, a maternal dead tissue, is important to keep seeds dormant over time, probably by shielding the seed living tissues from atmospheric oxygen.   Biochemical and genetical evidence previously established that cold promotes polyester accumulation in the seed coat and mutant seeds deficient in polyester biosynthesis have low dormancy and viability. However, it is unclear which seed coat structures, such as apoplastic barriers, are remodeled or created de novo in response to cold during seed development.  Combining histological and genetical approaches, a previously uncharacterized apoplastic barrier located in the outer integument 1 (oi1) cell layer was discovered. This barrier is strongly reinforced by cold and this process requires a MYB107 transcription factor , specifically expressed in oi1 cells. myb107 mutants is lacking the MYB107 TF, lacking the barrier and are less dormant, thus providing direct evidence that this barrier promotes dormancy in Arabidopsis. Overall design: To investigate MYB107 downstream targets in outer integument 1 (oi1) barrier and thus investigate oi1 barrrier composition, we compared WT and myb107 mutant transcriptome to identify MYB107 downstream targets at 22°C and with cold (13°C) transfert. To do so, we isolate RNA from WT and myb107 mutant at 11 Days After Pollination (DAP) grown at 22°C and with a 48h cold treatment. To have a better understanding of cold effect on WT, we also isolate RNA from WT with 6h cold treatment. Finally a 13DAP WT at 22°C was also included in the analysis to have an idea of the developmental effect on the transcriptome.