Cover illustration: Compared with the wild-type background (top), transgenic white spruces overexpressing (OE) Pinus taeda MYB1 (middle) and MYB8 (bottom) transcription factors display overlapping but also distinct phenotypes with regard to secondary cell wall biogenesis. Extensive RT-qPCR analysis shows that the transcript profiles of phenylpropanoid-related genes (blue) clearly overlapped in PtMYB1-OE and PtMYB8-OE spruces. More precisely, transcripts of the genes involved in monolignol (C4H to CAD) and lignan (PLR) pathways are significantly up-regulated in both transgenics, except those of COMT and CCoAOMT which were not affected by PtMYB8-OE. On the other hand, secondary cell wall-related transcripts (purple) are only impacted by PtMYB8-OE. This distinct response between both overexpressers is illustrated by the large deposition of secondary cell walls (pink staining) observed in cortical cells of the root, which is absent in wild-type and PtMYB1-OE backgrounds(Cover by C Bomal; See Bomal et al., pp. 3925-3939.)
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