Balanced activity of microRNA166/165 and its target transcripts from the class III homeodomain-leucine zipper family regulates root growth in Arabidopsis thaliana

Abstract

Overexpression of miR166/165 down-regulates target HD - ZIP IIIs and promotes root growth by enhancing cell division and meristematic activity, whereas overexpression of HD - ZIP IIIs inhibits root growth in Arabidopsis thaliana. Post-embryonic growth of higher plants is maintained by active meristems harbouring undifferentiated cells. Shoot and root apical meristems (SAM and RAM) utilize both similar and distinct signalling mechanisms for their maintenance in Arabidopsis thaliana. An important regulatory role in this context has the interaction of microRNAs with their target mRNAs, mostly encoding transcription factors. One class of microRNA166/165 (miR166/165) has been implicated in the maintenance of SAM and vascular patterning. Here, we show that miR166/165 plays an important role in root growth also by negatively regulating its target transcripts, HD-ZIP IIIs, in the RAM. While overexpression of miR166 promotes RAM activity, overexpression of its targets reduces RAM activity. These results reveal a conserved role of miR166/165 in the maintenance of SAM and RAM activity in A. thaliana.

Phytohormonal crosstalk modulates the expression of miR166/165s, target Class III HD-ZIPs, and KANADI genes during root growth in Arabidopsis thaliana

“…We have recently reported that miR166-Oe affects primary root growth through down regulation of HD-ZIP IIIs transcripts 19 . To investigate if the accumulation of miR166/165 and reduction in the expression of targets affected the response of roots to hormone treatment, we performed phenotypic analysis of wild type and miR166-Oe plants treated with different phytohormones (Fig.…”

“…Since miR166/165 cleaves and negatively regulates HD-ZIP III transcripts, differential root growth observed in miR166-Oe plants upon phytohormone treatment might be due to the altered expression levels of HD-ZIP IIIs 19 . At cellular level, the transcript level of total HD-ZIP IIIs is ultimately the result of both transcriptional regulation and post-transcriptional cleavage by miR166/165.…”

“…miR166/165 regulates diverse developmental processes including shoot apical meristem (SAM) maintenance, leaf polarity, floral development, and root development in plants by negatively regulating HD-ZIP III gene family members - PHABULOSA ( PHB ), PHAVOLUTA ( PHV ), REVOLUTA ( REV ), ARABIDOPSIS THALIANA HOMEOBOX 8 ( ATHB8 ) and ARABIDOPSIS THALIANA HOMEOBOX 15 ( ATHB15 ) 14–17 . Recently, miR166/165 has been shown to be involved in root development in Arabidopsis 18, 19 . KANADI genes ( KAN1 - KAN4) , members of GARP transcription factors family show expression pattern complementary to HD-ZIP IIIs and also regulate HD-ZIP IIIs expression and function 20 .…”

Root transcriptome of two contrasting indica rice cultivars uncovers regulators of root development and physiological responses

“…cDNA preparation and qRT-PCR was performed using the previously described method95. After checking the quality and spectrophotometric quantification, 2 μg RNA were converted into cDNA using M-MLV Reverse Transcriptase (Invitrogen, USA) following the manufacture’s protocol.…”

Apple <i>CALCINEURIN B-LIKE PROTEIN10</i> Genes have Evolved to be Novel Targets of MiR167s through Sequence Variation

“…Besides protein coding genes, small non-protein coding RNAs have recently been shown to be crucial components of gene regulatory network. These small RNAs (sRNAs, 19-24 bp long) regulate diverse developmental processes, including root and shoot growth 1 , by transcriptional or posttranscriptional gene silencing mechanisms 2 . The two sRNA classes, microRNAs (miRNAs) and small interfering RNAs (siRNAs) majorly comprise sRNA population in plants 3 .…”