-ROS-POD- System under Different Xylogenesis Scenarios in Karelian Birch Roth var. carelica (Mercl.) Hämet-Ahti).

Background: We studied which regulated superoxide radical / hydrogen peroxide ratio together with peroxidase (POD) activity and genes expression under different ways of apical meristem development during the xylem structural elements' formation in unique woody plants var. pendula with straight-grained wood and var. carelica with figured wood. The differentiation process predominanced in straight-grained wood ( var. ) or proliferation - in the figured wood. The investigation was conducted in the radial row (cambial zone - differentiating xylem - mature xylem) during the active cambial growth period.

Objective: The study aimed to study the xylogenesis processes occurring in the 16-year-old straight-grained silver birch ( Roth) and Karelian birch ( Roth var. carelica (Mercl.) Hämet-Ahti) with figured wood.

Methods: Hydrogen peroxide and superoxide radical contents and peroxidase activity were determined spectrophotometrically. Gene expression for family genes and the gene was assessed using qRT-PCR.

Results: Principal component analysis has confirmed trees with straight-grained and figured wood to be different according to UPBEAT1-ROS-POD- system functioning.

Conclusion: The higher superoxide radical/hydrogen peroxide ratio in figured Karelian birch, along with transcription factor and genes upregulation, distinguished it from straight-grained silver birch. This metabolic picture confirmed the shift of Karelian birch xylogenesis towards proliferation processes, accompanied by ROS and phenolic compounds' flow and POD activity.