169 7 report typing master pro v7
For example, miR169 affects plant responses to abiotic stress ( Zhang et al., 2011a), cold stress ( Zhou et al., 2008), salinity ( Zhao et al., 2009), nitrogen deficiency ( Zhao et al., 2011), and exposure to UV-B radiation ( Zhou et al., 2007). In Arabidopsis, numerous miRNAs affect plant development. MicroRNAs (miRNAs) can induce sequence-specific gene silencing transcriptionally and post-transcriptionally ( Voinnet, 2009), and regulate environmental responses, development, and hormone signaling in plants and animals ( Bartel, 2009). For example, fluctuation of ambient temperature correlates with an increase of respiration rates ( Atkin and Tjoelker, 2003), and higher ambient temperatures can shorten the time to flowering ( Fitter and Fitter, 2002). Small changes in temperature within the tolerable range, i.e., ambient temperature, also affect physiology and development of numerous plant species. For example, in Arabidopsis thaliana (Arabidopsis), exposure to a prolonged period of low temperature (i.e., vernalization) can shorten the time of flowering, especially in winter accessions. Temperature is one of the major factors that govern plant development and physiological processes. Taken together, our results suggest that HYH is a transcription factor that binds to a G-box-like motif in the MIR169a promoter and negatively regulates ambient temperature-responsive expression of MIR169a at higher temperatures in Arabidopsis. Consistent with the negative regulation of MIR169a by HYH, the diurnal levels of HYH mRNA and pri-miR169a showed opposite patterns. Transcript levels of pri-miR169a increased in hyh mutants and decreased in transgenic plants overexpressing HYH. Higher enrichment of HYH.2 protein on the promoter region of MIR169a was seen at 23☌, consistent with the presence of more HYH.2 protein in the cell at the temperature. Electrophoretic mobility shift assays and chromatin immunoprecipitation–quantitative PCR demonstrated that the HYH.2 protein, a predominant isoform of HYH, directly associated with a G-box-like motif in the 498-bp fragment of pri-miR169a. DNA-affinity chromatography followed by liquid chromatography-mass spectrometry analysis identified transcription factor HYH as a trans-acting factor that binds to the 498-bp promoter fragment of pri-miR169a.
GUS reporter assays revealed that the deletion of a 498-bp fragment (–1,505 to –1,007, relative to the major transcriptional start site) of MIR169a abolished its ambient temperature-responsive expression.
Absolute quantification identified MIR169a as the major locus producing miR169. In this study, we show that Elongated Hypocotyl 5-Homolog (HYH) directly binds to the promoter of MIR169a and negatively regulates its expression.
However, the transcription factors that regulate the expression of MIR169 have remained unknown.