592 / 2019-04-17 17:02:35

PRRs-TZF1-TOR molecular axis mediates circadian clock regulation on root architecture

Circadian clock,TOR signaling,root architecure

Growth and Development > Growth and Development

Circadian clock coordinates numerous plant growth and development processes including cell elongation in hypocotyl, whether or not it modulates cell proliferation in higher plants is largely unknown. Here we have found that Pseudo Response Regulators (PRRs), essential components of central oscillators, affect root meristem cell proliferation mediated by Target Of Rapamycin (TOR) signaling. The null mutants of PRRs display much reduced sensitivities to sugar-activated TOR signaling. We have subsequently identified Tandem Zinc Finger 1, encoding a processing body localized RNA-binding protein, as a direct target repressed by PRRs in mediating TOR signaling. Multiple lines of biochemical and genetic evidence have demonstrated that TZF1 acts downstream of PRRs to attenuate TOR signaling. Furthermore, TZF1 could directly bind 3’-UTR of TOR mRNA via its tandem zinc finger motif to affect TOR mRNA stability. Because other clock components, such as CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and EARLY FLOWERING 3 (ELF3), do not appear to be involved in TOR signaling, our findings support a notion that PRR-TZF1-TOR molecular axis mediates a clock-independent or a novel circadian output pathway to modulate root meristem cell proliferation by integrating both transcriptional and post-transcriptional regulatory mechanisms..