Calcium and Magnesium responses in Brassica rapa

A mapping population of Brassica rapa (BraIRRI, IMB211xR500) was grown under four external calcium and magnesium concentrations in controlled conditions. RNA was extracted and hybridised to the Affymetrix Brassica Exon 1.0 ST array. The aim of the experiment was to identify cis- and trans- expression quantitative trait loci. In total 279 samples were analysed. The parents of the mapping population were grown at all four treatment levels (LL, HL, LH, HH) with three biological replicates per treatment, plus 12 technical replicates (n=36). A 2x2 combination of external calcium and magnesium concentrations were imposed to give four treatments (LL, HL, LH, HH) as follows: the high (H) concentrations were 3.5 g L-1 (24 mM) CaCl2 and 3.04 g L-1 (15 mM) MgCl2 and the low (L) concentrations were 0.44 g L-1 (3 mM) CaCl2 and 0.2 g L-1 (1 mM) MgCl2 For the mapping population (total = 85 lines), 85 lines were analysed for the LL treatment, 81 lines were analysed for the LH treatment and 65 lines were analysed for the HL treatment. Twelve technical replicates were also analysed.