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KMID : 0578320110320010083
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Molecules and Cells
2011 Volume.32 No. 1 p.83 ~ p.88
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The Role of the miR399-PHO2 Module in the Regulation of Flowering Time in Response to Different Ambient Temperatures in Arabidopsis thaliana
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Kim Wan-Hui
Ahn Hae-Ji
Tzyy-Jen Chiou
Ahn Ji-Hoon
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Abstract
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A moderate change in ambient temperature significantly affects plant physiology including flowering time. MiR399 and its target gene PHOSPHATE 2 (PHO2) are known to play a role in the maintenance of phosphate homeostasis. However, the regulation of flowering time by the miR399-PHO2 module has not been investigated. As we have previously identified miR399 as an ambient temperature-res-ponsive miRNA, we further investigated whether a change in expression of the miR399-PHO2 module affects flowering time in response to ambient temperature changes. Here, we showed that miR399b-overexpressing plants and a loss-of-function allele of PHO2 (pho2) exhibited an early flowering phenotype only at normal temperature (23oC). Interestingly, their flowering time at lower temperature (16ºC) was similar to that of wild-type plants, suggesting that alteration in flowering time by miR399 and its target PHO2 was seen only at normal temperature (23oC). Flowering time ratio (16oC/23oC) revealed that miR399b-overex-pressing plants and pho2 mutants showed increased sensitivity to ambient temperature changes. Expression analysis indicated that expression of TWIN SISTER OF FT (TSF) was increased in miR399b-overexpressing plants and pho2 mutants at 23oC, suggesting that their early flo-wering phenotype is associated with TSF upregulation. Taken together, our results suggest that miR399, an am-bient temperature-responsive miRNA, plays a role in am-bient temperature-responsive flowering in Arabidopsis.
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KEYWORD
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ambient temperature, flowering time, MiR399, PHO2, TSF
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