Environmental stresses modulate abundance and timing of alternatively spliced circadian transcripts in Arabidopsis

Author(s): Sergei A. Filichkin, Jason S. Cumbie, Palitha Dharmawardhana, Pankaj Jaiswal, Jeff H. Chang, Saiprasad G. Palusa, A.S.N. Reddy, Molly Megraw, Todd C. Mockler
Date of Publication: November 2015

Environmental stresses profoundly altered accumulation of nonsense mRNAs including intron-retaining (IR) transcripts in Arabidopsis. Temporal patterns of stress-induced IR mRNAs were dissected using both oscillating and non-oscillating transcripts. Broad-range thermal cycles triggered a sharp increase in the long IR CCA1 isoforms and altered their phasing to different times of day. Both abiotic and biotic stresses such as drought or Pseudomonas syringae infection induced a similar increase. Thermal stress induced a time delay in accumulation of CCA1 I4Rb transcripts, whereas functional mRNA showed steady oscillations. Our data favor a hypothesis that stress-induced instabilities of the central oscillator can be in part compensated through fluctuations in abundance and out-of-phase oscillations of CCA1 IR transcripts. Taken together, our results support a concept that mRNA abundance can be modulated through altering ratios between functional and nonsense/IR transcripts. SR45 protein specifically bound to the retained CCA1 intron in vitro, suggesting that this splicing factor could be involved in regulation of intron retention. Transcriptomes of nonsense-mediated mRNA decay (NMD)-impaired and heat-stressed plants shared a set of retained introns associated with stress- and defense-inducible transcripts. Constitutive activation of certain stress response networks in an NMD mutant could be linked to disequilibrium between functional and nonsense mRNAs.

Citation: Filichkin, S.A., Cumbie, J.S., Dharmawardhana, P., Jaiswal, P., Chang, J.H., Palusa, S.G., Reddy, A.S.N., Megraw, M., Mockler, T.C. Environmental Stresses Modulate Abundance and Timing of Alternatively Spliced Circadian Transcripts in Arabidopsis. Molecular Plant, Volume 8, Issue 2, p207–227, 2 February 2015
Team(s): Plant Team