source-sink-dynamics
Source-sink dynamics describes the movement of photosynthetically fixed carbon and other resources from productive 'source' tissues (such as mature leaves) to metabolically active or storage 'sink' tissues (such as roots, seeds, and developing organs). Understanding this balance is central to plant biology because it governs growth, yield, and how plants allocate resources under varying environmental conditions. Manipulating source-sink relationships is a key target in efforts to improve crop productivity and stress resilience.
open_in_new WikipediaPubMed · 2026-04-15
Scientists discovered that roots need well-functioning internal plumbing (phloem) not just to receive sugar from leaves, but to send signals back that tell leaves how much sugar to produce — a two-way communication system that controls whole-plant growth.
Root growth defects in phloem-deficient mutants are root-autonomous — grafting normal leaves onto mutant roots did not rescue root growth, proving the problem originates in the roots themselves.
Damaged root phloem restricted growth of healthy wild-type shoots grafted onto mutant roots, demonstrating that impaired sink tissue sends negative feedback signals that suppress source-leaf activity.
Carbon partitioning and phloem transport velocity were both reduced in mutants, with double-mutant (ops opl2) plants showing stronger defects than single-mutant (ops) plants, and only double-mutant root growth was partially rescued by external sucrose.
