Photoperiod signals provide important cues by which plants regulate their growth and development in response to predictable seasonal changes. Phytochromes, a family of red and far-red light receptors, play critical roles in regulating flowering time in response to changing photoperiods. A previous study showed that loss-of-function mutations in either PHYB or PHYC result in large delays in heading time and in the differential regulation of a large number of genes in wheat plants grown in an inductive long day (LD) photoperiod. We found that under non-inductive short-day (SD) photoperiods, phyB-null and phyC-null mutants were taller, had a reduced number of tillers, longer and wider leaves, and headed later than wild-type (WT) plants. The delay in heading between WT and phy mutants was greater in LD than in SD, confirming the importance of PHYB and PHYC in accelerating heading date in LDs. Both mutants flowered earlier in SD than LD, the inverse response to that of WT plants. In both SD and LD photoperiods, PHYB regulated more genes than PHYC. We identified subsets of differentially expressed and alternatively spliced genes that were specifically regulated by PHYB and PHYC in either SD or LD photoperiods, and a smaller set of genes that were regulated in both photoperiods. We found that photoperiod had a contrasting effect on transcript levels of the flowering promoting genes VRN-A1 and PPD-B1 in phyB and phyC mutants compared to the WT. Our study confirms the major role of both PHYB and PHYC in flowering promotion in LD conditions. Transcriptome characterization revealed an unexpected reversion of the wheat LD plants into SD plants in the phyB-null and phyC-null mutants and identified flowering genes showing significant interactions between phytochromes and photoperiod that may be involved in this phenomenon. Our RNA-seq data provides insight into light signaling pathways in inductive and non-inductive photoperiods and a set of candidate genes to dissect the underlying developmental regulatory networks in wheat.

中文翻译：

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短期和长期光周期下phyB和phyC功能丧失突变对小麦转录组的影响。

光周期信号为植物响应可预测的季节变化调节其生长和发育提供了重要线索。植物色素是红色和远红色光受体的一个家族，在响应不断变化的光周期时，在调节开花时间方面起着至关重要的作用。先前的研究表明，PHYB或PHYC中功能丧失的突变会导致在诱导长日（LD）光周期中生长的小麦植株的抽穗时间大大延迟，并导致大量基因的差异调控。我们发现，在非感应短日（SD）光周期下，phyB-null和phyC-null突变体较高，分ers数减少，叶片更长和更宽，并且比野生型（WT）植物的花期晚。LD中WT和phy突变体之间前进的延迟大于SD中，确认PHYB和PHYC在加快LD航向中的重要性。两种突变体在SD上的开花都比LD早，这与野生型植物相反。在SD和LD光周期中，PHYB比PHYC调控更多的基因。我们确定了差异表达和选择性剪接的基因的子集，这些子集在SD或LD光周期中均受PHYB和PHYC特异调节，在这两个光周期中均受较小的基因集。我们发现与WT相比，光周期对phyB和phyC突变体中促花基因VRN-A1和PPD-B1的转录水平具有相反的影响。我们的研究证实了PHYB和PHYC在LD条件下促进开花的主要作用。转录组表征揭示了在phyB-null和phyC-null突变体中，小麦LD植物出乎意料地还原为SD植物，并鉴定出开花基因，表明该现象可能与植物色素和光周期之间存在显着相互作用。我们的RNA-seq数据可洞察感应性和非感应性光周期中的光信号通路，以及一组候选基因来剖析小麦的基本发育调控网络。