Recovery after deficiency: systemic copper prioritization and partitioning in the leaves and stems of hybrid poplar

Copper (Cu) is important for many aspects of plant function including photosynthesis. It has been suggested that photosynthesis, especially in young leaves, is prioritized for Cu delivery after deficiency in hybrid poplar. To determine relative Cu delivery prioritization, we enriched hydroponic plant growth media of Cu-deficient poplar with 98% Cu-65 and tracked Cu delivery after deficiency to young leaves, mature leaves and stems. Young leaves acquired similar to 58% more Cu-65 on Day 1 and similar to 65% more Cu-65 by Day 3 compared with mature leaves. Additionally, stomatal conductance (g(s)) was measured on leaves for 6 weeks and during a 3-day Cu-65 pulse resupply period. During deficiency, mature leaves maintained a higher g(s) than younger leaves but 3 days after Cu resupply the younger leaves that had recovered showed the highest g(s). In conclusion, these results provide a quantitative understanding of how Cu is systemically transported and distributed to photosynthetic and stem tissues.

Automated summary

The study reveals the prioritization mechanism of copper delivery in plants, showing that young leaves absorb copper faster after deficiency and have the highest stomatal conductance after recovery.