MicroRNAs (miRNAs) have been recognized as important regulators in plant response to nutrient deficiencies. Of particular interest is the discovery that miR399 functions systemically in the maintenance of phosphate (Pi) homeostasis in response to external Pi fluctuation. Recent studies have further implicated both miR399 and sugars (mainly sucrose) as potential signal molecules in the shoot-to-root communication of phosphorus (P) status. Given that both miR399 and sucrose are transported via the phloem, their potential interaction (or cross-talk) along the signaling pathway is especially appealing for further exploration. In this mini-review, we highlight recent progress in unraveling crucial roles of both sucrose and miR399 in P-deficiency signaling. In particular, we further discuss recent findings that photosynthetic carbon (C) assimilation and subsequent partitioning, by overriding signaling of low external Pi, act as checkpoints upstream of miR399 for the onset of a systemic P-deficiency status.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the continuous funding from United States Department of Agriculture, National Research Initiative, CSREES Grant Number 2005-35100-16002; US Department of Agriculture, Agricultural Research Service CRIS Number 3640-21000-024-00D; and University of Minnesota, Specific Cooperative Agreement Number 58-3640-9-750. The authors also wish to thank Ginger Walker for proofreading of the manuscript.
- P deficiency
- Systemic signaling