Minisymposium 17: Mineral Nutrition
Add
this abstract to my Itinerary
Abs #
M1703: Regulation of Phosphate Homeostasis by microRNA in Arabidopsis
|
|
Presenter: |
Chiou, Tzyy-Jen Contact Presenter |
Authors | Lin, Shu-I (A) (C) Aung, Kyaw (A) (B) Wu, Chia-Chune (A) Chiang, Su-Fen (A) Huang, Yu-Ting (A) Su, Chun-lin (A) Chiou, Tzyy-Jen (A) (B) | | Affiliations: |
(A): Institute of BioAgricultural Sciences, Academia Sinica
(B): Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica
(C): National Graduate Institute of Life Sciences, National Defense Medical Center
|
|
|
A mechanism by which plants regulate Pi homeostasis to adapt to environmental changes in Pi availability was revealed. This mechanism involves the suppression of a ubiquitin-conjugating E2 enzyme by a specific microRNA, miR399. Upon Pi starvation, the miR399 is upregulated and its target gene, a ubiquitin-conjugating E2 enzyme (UBC24), is downregulated in Arabidopsis. Accumulation of the UBC24 transcript is suppressed in transgenic Arabidopsis overexpressing miR399. Transgenic plants accumulated 5 to 6 times the normal Pi level in shoots and displayed Pi toxicity symptoms that were phenocopied by a loss-of-function UBC24 mutant. Pi toxicity was caused by increased Pi uptake and translocation of Pi from roots to shoots, and retention of Pi in the shoots. Kinetic analyses showed that greater Pi uptake is due to increased Vmax. Moreover, we uncovered that a previously identified Pi overaccumulator, pho2, is caused by a single nucleotide mutation resulting in early termination within the UBC24 gene. Promoter::reporter analyses indicated that miR399 and UBC24 are co-localized in the vascular cylinder. This observation not only provides important insights into the interaction between miR399 and UBC24 mRNA but also supports their systemic function in Pi translocation. These results provide the evidence that miRNA controls Pi homeostasis by regulating the expression of a component of the proteolysis machinery in plants.
