Scots pine (Pinus sylvestris L.) is a species of tree with heartwood (HW), which is forming during aging of sapwood (SW). Due to clear-cut border between SW and HW P. sylvestris should be used as a model woody plant for studying patterns of HW formation. Currently, molecular genetic methods are used to study the processes of trunk tissues formation in woody plants often. A feature of trunk tissues of coniferous trees is a high content of secondary metabolites, a low content of nucleic acids, and potential partial degradation of RNA. In this work we discuss the choice of most successful method for extraction a high-quality RNA for real-time PCR (RT-PCR) in P. sylvestris trunk tissues along the radial vector “conductive phloem/cambial zone – differentiating xylem – exterior part of SW (1–2 annual rings) – interior part of SW (1–2 annual rings afore transition zone (TZ)) – TZ (2 annual rings afore HW)” for reproducible RT-PCR data. The expression stability of six potential reference genes (Actin1, α-Tubulin, β-Tubulin, Ef1a, GAPDH, UBQ) was assessed in all describe tissues. Differences in expression levels of target genes are shown by data normalization using reference genes with different stability of expression.
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