Divergent N-deficiency-dependent senescence initiation and transcriptome response in developmentally old and young Brassica napus leaves

To identify oilseed rape genes with a potential role in N-remobilization during leaf senescence of developmentally old leaves in the lower canopy and young leaves in the upper canopy, transcriptomes of leaf number 4 and leaf number 8 of B. napus (cultivar Mozart) were analysed at different harvest time points under mild N deficiency and optimal N fertilization. Brassica napus, spring cultivar Mozart, was grown in seasonal climate simulating growth chambers under mild N defciency (NL: 75 kg N/ha NH4NO3) or optimal N supply (NO: 150 kg N/ha NH4NO3). The transcriptomes of leaf number 4 at 78, 85, 92 and 99 days after sowing (DAS) and leaf number 8 at 92 and 106 DAS were determined in three separate plants each (biological replicates R1 - R3).