Fig. 4

The expression profiles of plastid biogenesis genes during embryo formation in ‘Jersey’ and ‘Mercada’ cultures. a, b Relative expression level of nuclear-encoded (a) and plastid-encoded (b) genes related to plastid transcription: NEP (RpoTp), sigma factors (Sig2, Sig6) and PEP (rpoA, rpoB, rpoC1 and rpoC2). c Relative expression level of plastid-encoded 16S and 23S rRNA genes. Graphs show mean values of n ≥ 3 with SEM. The relative expression level was normalised to ML microspores of cv. ‘Jersey’. An asterisk presents a value significantly different between cultivars at a certain day of culture. A hash indicates a value significantly different from the preceding day of culture within cultivar (Tukey’s test, P < 0.05). ML – mid-to-late microspore, PM – pre-treated microspores, dC – day of culture