Filichkin Sergei A, Cumbie Jason S, Dharmawadhana J Palitha, Jaiswal Pankaj, Chang Jeff H, Palusa Saiprasad G, Reddy A S N, Megraw Molly, Mockler Todd C
Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, 97331, USA
Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA.
Mol Plant. 2014 Nov 3. doi: 10.1093/mp/ssu130.
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 intron retaining CCA1 isoforms and altered their phasing to different times of day. Both abiotic and biotic stresses such as drought or P. syringae infection induced 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. Altogether, 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 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.
环境胁迫深刻改变了拟南芥中包括内含子保留（IR）转录本在内的无义mRNA的积累。利用振荡和非振荡转录本剖析了胁迫诱导的IR mRNA的时间模式。广泛的热循环触发了长内含子保留的CCA1异构体的急剧增加，并将它们的相位改变到一天中的不同时间。干旱或丁香假单胞菌感染等非生物和生物胁迫均诱导了类似的增加。热胁迫导致CCA1 I4Rb转录本积累出现时间延迟，而功能性mRNA则表现出稳定的振荡。我们的数据支持这样一种假说，即胁迫诱导的中央振荡器的不稳定性可以部分通过CCA1 IR转录本丰度的波动和异相振荡得到补偿。总之，我们的结果支持一个概念，即mRNA丰度可以通过改变功能性和无义/IR转录本之间的比例来调节。SR45蛋白在体外特异性结合到保留的CCA1内含子上，表明这种剪接因子可能参与内含子保留的调控。NMD缺陷和热胁迫植物的转录组共享一组与胁迫和防御诱导转录本相关的保留内含子。NMD突变体中某些胁迫反应网络的组成型激活可能与功能性和无义mRNA之间的不平衡有关。
