Graft-transmissible induction of potato tuberization by the microRNA miR172

Abstract

The photoreceptor phytochrome B (PHYB) and the homeodomain protein BEL5 are involved in the response of potato tuber induction to the photoperiod. However, whether they act in the same tuberization pathway is unknown. Here we show the effect of a microRNA, miR172, on this developmental event. miR172 levels are higher under tuber-inducing short days than under noninductive long days and are upregulated in stolons at the onset of tuberization. Overexpression of this microRNA in potato promotes flowering, accelerates tuberization under moderately inductive photoperiods and triggers tuber formation under long days. In plants with a reduced abundance of PHYB, which tuberize under long days, both BEL5 mRNA and miR172 levels are reduced in leaves and increased in stolons. This, together with the presence of miR172 in vascular bundles and the graft transmissibility of its effect on tuberization, indicates that either miR172 might be mobile or it regulates long-distance signals to induce tuberization. Consistent with this, plants overexpressing miR172 show increased levels of BEL5 mRNA, which has been reported to be transmissible through grafts. Furthermore, we identify an APETALA2-like mRNA containing a miR172 binding site, which is downregulated in plants overexpressing miR172 and plants in which PHYB is silenced. Altogether, our results suggest that miR172 probably acts downstream of the tuberization repressor PHYB and upstream of the tuberization promoter BEL5 and allow us to propose a model for the control of tuberization by PHYB, miR172 and BEL5.

Characterization of the pumpkin Translationally-Controlled Tumor ProteinCmTCTP

“…25 A large array of potentially signaling molecules has been identified in the phloem translocation stream, including proteins and different species of RNAs. [26][27][28][29][30][31][32] Since it is likely that the enucleate sieve element does not engage in protein synthesis, such RNAs probably constitute signaling molecules. We have previously found several RNAs in phloem sap of pumpkin infected with CMV.…”

The control of developmental phase transitions in plants

“…Interestingly, MIR172 overexpression has been shown to promote flowering and also tuberization in potato (Martin et al, 2009). Moreover, the effect of miR172 on tuberization has been found to be graft transmissible (Martin et al, 2009).…”

“…Moreover, the effect of miR172 on tuberization has been found to be graft transmissible (Martin et al, 2009). Whether longdistance movement of miR172 itself was responsible for this phenomenon is unclear.…”

LEUNIG and SEUSS co-repressors regulate miR172 expression in Arabidopsis flowers

“…A model summarizing current understanding of A-C antagonism miR172 regulates many important developmental processes in diverse plant species (Aukerman and Sakai, 2003;Chen, 2004;Chuck et al, 2007;Jung et al, 2007;Lauter et al, 2005;Martin et al, 2009;Wu et al, 2009). Whereas much attention has focused on finding the targets of miRNAs and on their biogenesis and metabolism, less is known about their transcriptional regulation.…”