Regulation of HD-ZIP III Genes by MicroRNA 165
1Department of Plant Biology; University of Georgia; Athens, Georgia USA.
Abstract:
MicroRNAs (miRNAs) 165 and 166 are able to cleave their target mRNAs of HD-ZIP III genes, thus regulating the functions of these genes. Although it is generally accepted that both miR165 and miR166 perform the same functions in the regulation of HD-ZIP III genes in Arabidopsis, no experimental data are available to support this notion. Recent work has shown that overexpression of miR166 downregulates the expression of three HD-ZIP III genes, ATHB-9/PHV, ATHB-14/PHB and ATHB-15, which in turn recapitulates the phenotypes of simultaneous loss-of-function mutations of these genes. In the March issue of Plant & Cell Physiology, we have demonstrated that overexpression of miR165 leads to the down-regulation of all five HD-ZIP III genes, and concomitantly recapitulates the phenotypes of loss-of-function mutation of IFL1/REV and those of simultaneous loss-of-function mutations of IFL1/REV, ATHB-9/PHV and ATHB-14/PHB. These results indicate that miR165 and miR166 differentially regulate the functions of HD-ZIP III genes in Arabidopsis. In this addendum, we show that overexpression of the antisense form of the miR165a gene leads to formation of amphivasal vascular bundles, a phenotype reminiscent of that of the dominant mutation of IFL1/REV. This finding provides direct evidence for a role of miR165 in regulation of vascular patterning.
Insights
MicroRNAs (miRNAs) 165 and 166 differentially regulate HD-ZIP III genes in Arabidopsis. miR165 targets all five HD-ZIP III genes, impacting vascular patterning, while miR166 targets three, affecting gene expression.
Area of Science:
- Plant molecular biology
- Gene regulation
- Developmental biology
Background:
- MicroRNAs (miRNAs) 165 and 166 are known to target HD-ZIP III genes.
- It is widely assumed that miR165 and miR166 have identical functions in regulating HD-ZIP III genes in Arabidopsis.
- Previous studies showed miR166 overexpression affects three HD-ZIP III genes.
Purpose of the Study:
- To experimentally investigate and compare the regulatory roles of miR165 and miR166 on HD-ZIP III genes in Arabidopsis.
- To determine if miR165 and miR166 exhibit differential regulation of HD-ZIP III genes.
- To provide evidence for the specific role of miR165 in vascular patterning.
Main Methods:
- Overexpression of miR165 and miR166 in Arabidopsis.
- Analysis of HD-ZIP III gene expression levels (ATHB-9/PHV, ATHB-14/PHB, ATHB-15, IFL1/REV).
- Observation and characterization of plant phenotypes resulting from miRNA overexpression, including vascular bundle morphology.
Main Results:
- Overexpression of miR165 downregulated all five HD-ZIP III genes and mimicked loss-of-function phenotypes for IFL1/REV and combinations thereof.
- Overexpression of miR166 downregulated three HD-ZIP III genes (ATHB-9/PHV, ATHB-14/PHB, ATHB-15), recapitulating their combined loss-of-function phenotypes.
- Overexpression of antisense miR165a led to amphivasal vascular bundles, indicating miR165's role in vascular patterning.
Conclusions:
- miR165 and miR166 exhibit distinct regulatory functions on HD-ZIP III genes in Arabidopsis.
- miR165 plays a significant role in regulating vascular patterning.
- The findings challenge the assumption of identical functions for miR165 and miR166 in this context.
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