Nitrogen starvation and cultivar-specific leaf senescence in winter oilseed rape (Brassica napus)

To identify marker genes that are specific for N starvation-induced leaf senescence and suitable to detect cultivar differences at early senescence stages prior to chlorophyll loss, the transcriptomes of leaves of two B. napus cultivars differing in stay-green characteristics and N efficiency were analysed four days after senescence induction by the senescence inducers N starvation, leaf shading and leaf detaching. Brassica napus cultivars Apex (11; N-efficient) and Capitol (12 N-inefficient) were pre-cultured in hydroponics for 28 days at optimal N supply before induction of leaf senescence by (i) N starvation, (ii) leaf shading and (iii) leaf detachment. After four days of treatment the transcriptome of leaf number 3 was determined in three separate plants (biological replicates r1 - r3).