UV‐B radiation delays flowering time through changes in the PRC2 complex activity and miR156 levels in Arabidopsis thaliana

Abstract

UV-B is a high-energy component of the solar radiation perceived by the plant and induces a number of modifications in plant growth and development, including changes in flowering time. However, the molecular mechanisms underlying these changes are largely unknown. In the present work, we demonstrate that Arabidopsis plants grown under white light supplemented with UV-B show a delay in flowering time, and this developmental reprogramming is mediated by the UVR8 photoreceptor. Using a combination of gene expression analyses and UV-B irradiation of different flowering mutants, we gained insight into the pathways involved in the observed flowering time delay in UV-B-exposed Arabidopsis plants. We provide evidence that UV-B light downregulates the expression of MSI1 and CLF, two of the components of the polycomb repressive complex 2, which in consequence drives a decrease in H3K27me3 histone methylation of MIR156 and FLC genes. Modification in the expression of several flowering time genes as a consequence of the decrease in the polycomb repressive complex 2 activity was also determined. UV-B exposure of flowering mutants supports the involvement of this complex in the observed delay in flowering time, mostly through the age pathway.

Arabidopsis RUP2 represses UVR8-mediated flowering in noninductive photoperiods

“…It is noteworthy that wild type developed slower and flowered later under SD + UV than under SD − UV conditions (e.g., Figs. 1, 4A-C, 5C-E), which is in agreement with a recent report (Dotto et al 2018). Interestingly, this delayed flowering was partially UVR8-dependent (Fig.…”

“…1F,G; Supplemental Fig. S1) and has been linked previously to the age pathway of flowering (Dotto et al 2018). The potential interplay between the effects of UVR8 signaling on the age and photoperiod pathways remains to be determined; however, it is clear that the effect of RUP2 mutation on the photoperiodic pathway overrides the potential effect of UVR8 hyperactivity in rup2 on the age pathway.…”

Epigenetic Regulation of Juvenile-to-Adult Transition in Plants

“…Under salt or drought stress conditions, miR156 was induced to maintain plants in the juvenile phase for a relatively longer time; when they were returned to favorable conditions, miR156 was suppressed to accelerate the developmental transition ( Cui et al, 2014 ). Under UV-B radiation conditions, the PRC2-mediated H3K27me3 modification in the MIR156A/MIR156C loci was decreased, and the corresponding up-regulation of miR156 delayed juvenile-to-adult transition ( Dotto et al, 2018 ). Other studies also indicate that the expression of miR156 is responsive to ambient temperature ( Stief et al, 2014 ), phosphate starvation ( Hsieh et al, 2009 ), CO 2 treatment ( May et al, 2013 ), suggesting a tight interaction between juvenile-to-adult transition and environment through the miR156/157-SPL pathway.…”

Flowering‐mediated root‐fungus symbiosis loss is related to jasmonate‐dependent root soluble sugar deprivation

“…To determine whether P. liquidambari inoculation shortens flowering time through regulating flowering pathway, the expression of key flowering time regulators, including FLC , FT , SOC1 , and LFY in rosette leaves was analysed. During the flowering pathway of Arabidopsis , the MADS‐box gene FLC is the major repressor of plant flowering through negatively regulating the expression of floral integrators, such as FT , SOC1 , and LFY (Dotto, Gómez, Soto, & Casati, ; Putterill & Varkonyi‐Gasic, ). Using RT‐qPCR with independent samples, we found a slight but not significant difference in FLC expression following P. liquidambari inoculation (Figure i).…”