Abstract
In plants, sugars such as glucose act as signalling molecules that promote changes in gene expression programmes that impact on growth and development. Recent evidence has revealed the potential importance of controlling mRNA decay 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 dcl1-11) and miRNA activity (ago1-25) was evaluated. All mutants exhibited a glucose hyposensitive phenotype from germination up to seedling establishment, indicating that miRNA regulatory pathways are involved in the glucose-mediated delay of early seedling development. The expression profile of 200 miRNA primary transcripts (pri-miRs) was evaluated by large-scale quantitative real-time PCR profiling, which revealed 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-miR by glucose. Furthermore, the expression of several miRNA target genes was found to be deregulated in response to glucose in the miRNA machinery mutants ago1-25, dcl1-11, and hyl1-2. Also, in these mutants, glucose promoted misexpression of genes for the three abscisic acid signalling elements ABI3, ABI4, and ABI5. Thus, miRNA regulatory pathways play a role in the adjustments of growth and development triggered by glucose signalling.
Highlights
Photosynthesis-derived sugars are the main source of car- and Yoo, 2011; Li et al, 2011), sucrose (Vaughn et al, 2002), bon skeletons and energy in plants
In order to get a better understanding of glucose-mediated development modulation involving miRNArelated regulatory pathways, early seedling development of mutants impaired in miRNA biogenesis and miRNA activity was evaluated
The mature miRNA is recognized by ARGONAUTE1 (AGO1) which is in turn integrated into the RNA-induced silencing complex (RISC) through a process that might require HYPONASTIC LEAVES1 (HYL1) activity (Eamens et al, 2009). miRNA complementarity to specific mRNA guides RISC-mediated target mRNA cleavage and/or translational repression (Mi et al, 2008; Voinnet, 2009)
Summary
Photosynthesis-derived sugars are the main source of car- and Yoo, 2011; Li et al, 2011), sucrose (Vaughn et al, 2002), bon skeletons and energy in plants. Sugar signalling depends on the integration with other nutrient levels, such as phosphate, sulphate, and nitrogen, which are tightly related with circadian regulation and are required for proper plant development expression programmes (Rolland et al, 2006) Sugars such as sucrose or glucose have been shown to interact with the hormones abscisic acid (ABA), ethylene (Yanagisawa et al, 2003; Karve et al, 2012), auxin, and cytokinin (Moore et al, 2003; Sairanen et al, 2012) in regulating plant development (Rolland et al, 2006) and stress responses (Price et al, 2003; Jossier et al, 2009). This phenotype was correlated with the regulation of the expression of a set of 38 pri-miRs by 4% glucose, indicating that miRNA-related regulatory processes modulate the glucose-dependent delay of seedling development
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