A1 Refereed original research article in a scientific journal
A miRNA involved in phosphate-starvation response in Arabidopsis
Authors: Fujii, H; Chiou, TJ; Lin, SI; Aung, K; Zhu, JK
Publisher: CELL PRESS
Publishing place: CAMBRIDGE
Publication year: 2005
Journal: Current Biology
Journal name in source: CURRENT BIOLOGY
Journal acronym: CURR BIOL
Volume: 15
Issue: 22
First page : 2038
Last page: 2043
Number of pages: 6
ISSN: 0960-9822
DOI: https://doi.org/10.1016/j.cub.2005.10.016
Abstract
Although microRNAs (miRNAs) have been documented to regulate development in plants and animals (1, 2], the function of miRNAs in physiology is unclear. miR399 has multiple target sites in the 5' untranslated region (UTR) of a gene encoding a putative ubiquitin-conjugating enzyme (UBC) in Arabidopsis thaliana [3]. We report here that miR399 was highly induced, whereas the target UBC mRNA was reduced by low-phosphate (Pi) stress. In transgenic plants with constitutive expression of miR399, UBC mRNA accumulation was suppressed even under high Pi. The expression of transgene UBC mRNA with 5'UTR miR399 target sites, but not the one without 5' UTR, was reduced under low-Pi condition. Furthermore, transgenic Arabidopsis plants with constitutive expression of miR399 accumulated more Pi than the wild-type, and transgenic plants expressing the UBC mRNA without 5' UTR (miRNA-deregulated) showed less inhibition of primary root growth and less induction of a PI transporter gene by low-Pi stress than those of wildtype plants. We conclude that miR399 downregulates UBC mRNA accumulation by targeting the 5' UTR, and this regulation is important for plant responses to Pi starvation. The results suggest that miRNAs have functional roles for plants to cope with fluctuations in mineral-nutrient availability in the soil.
Although microRNAs (miRNAs) have been documented to regulate development in plants and animals (1, 2], the function of miRNAs in physiology is unclear. miR399 has multiple target sites in the 5' untranslated region (UTR) of a gene encoding a putative ubiquitin-conjugating enzyme (UBC) in Arabidopsis thaliana [3]. We report here that miR399 was highly induced, whereas the target UBC mRNA was reduced by low-phosphate (Pi) stress. In transgenic plants with constitutive expression of miR399, UBC mRNA accumulation was suppressed even under high Pi. The expression of transgene UBC mRNA with 5'UTR miR399 target sites, but not the one without 5' UTR, was reduced under low-Pi condition. Furthermore, transgenic Arabidopsis plants with constitutive expression of miR399 accumulated more Pi than the wild-type, and transgenic plants expressing the UBC mRNA without 5' UTR (miRNA-deregulated) showed less inhibition of primary root growth and less induction of a PI transporter gene by low-Pi stress than those of wildtype plants. We conclude that miR399 downregulates UBC mRNA accumulation by targeting the 5' UTR, and this regulation is important for plant responses to Pi starvation. The results suggest that miRNAs have functional roles for plants to cope with fluctuations in mineral-nutrient availability in the soil.
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