Sugar infusion into trees: A novel method to study tree carbon relations and its regulations

Area of Science:

• Plant physiology
• Plant biochemistry
• Forest ecology

Background:

• Understanding plant carbon (C) metabolism is crucial for addressing issues like C limitation or starvation.
• Current experimental methods lack the precision to thoroughly investigate plant C physiology.
• Exogenous sugar uptake and metabolism in trees remain incompletely understood.

Purpose of the Study:

• To develop and validate a novel tree infusion method for studying carbon uptake and metabolism.
• To investigate the translocation and metabolic fate of exogenous sugars in different tree species.
• To assess the feasibility of xylem versus phloem infusion for delivering sugars to trees.

Main Methods:

• ¹³C-labelled glucose was infused into the xylem and phloem of bonsai (Ficus microcarpa), maple (Acer pseudoplatanus), and Scots pine (Pinus sylvestris) trees.
• ¹³C-signal was traced in plant organic matter and respiration over ten weeks.
• Respiration measurements were conducted on young maple trees to analyze respired CO₂.

Main Results:

• Xylem infusion significantly increased ¹³C levels in both above- and belowground tissues of bonsai trees.
• In Scots pines, xylem infusion elevated ¹³C in xylem, while phloem infusion increased it in phloem.
• Maple trees showed elevated ¹³C in respired CO₂ following xylem infusion.

Conclusions:

• Trees can effectively translocate and metabolize exogenous sugars supplied via infusion.
• Xylem infusion is a more practical method than phloem infusion due to the thin phloem layer.
• This novel infusion technique offers significant potential for advancing research on whole-plant carbon balance and its regulation under stress.