Involvement of microRNA-related regulatory pathways in glucose-mediated control of Arabidopsis early seedling development

In plants, sugars such as glucose act as signaling molecules that promote changes in gene expression programs impacting on growth and development. Recent evidences have revealed the potential participation of mRNA decay control in some aspects of glucose-mediated regulatory responses suggesting a role of microRNAs (miRNAs) in these responses. In order to get a better understanding of glucose-mediated development modulation involving miRNA-related regulatory pathways, early seedling development of mutants impaired in miRNA biogenesis (hyl1-2) and miRNA-activity (ago1-25) were evaluated. Both mutants exhibited a glucose hyposensitive phenotype from germination up to seedling establishment, indicating that miRNA regulatory pathways may be involved in the glucose-mediated delay of early seedling development. The expression profile of 200 primary miRNA transcripts (pri-miRs) were evaluated by large-scale quantitative real-time polymerase chain reaction (qRT-PCR) profiling revealing that 38 pri-miRs were regulated by glucose. For several of them, the corresponding mature miRNAs are known to participate directly or indirectly in plant development, and their accumulation was shown to be co-regulated with the pri-miRNA by glucose. These data indicate that deficiency in miRNA machinery leads to a deregulated expression of several miRNA target genes in response to glucose. Also, such deficiencies result in glucose-promoted misexpression of genes for the three Abscisic Acid signaling elements ABI3, ABI4 and ABI5. Thus, miRNA-regulatory pathways play a role in the adjustments of growth and development triggered by glucose signaling. Three samples, including untreated control, 2% glucose-treated and 2% mannitol-treated samples.