背景回顧:During leaf senescence, the final stage of leaf development, nutrients are recycled from leaves to other organs, and therefore proper control of senescence is thus critical for plant fitness.
提出問題:Although substantial progress has been achieved in understanding leaf senescence in annual plants, the molecular factors that control leaf senescence in perennial woody plants are largely unknown.
主要研究:Using RNA sequencing, we obtained a high-resolution temporal profile of gene expression during autumn leaf senescence in poplar (Populus tomentosa).
結果1-基因共表達網絡:Identification of hub transcription factors (TFs) by co-expression network analysis of genes revealed that senescence-associated NAC-family TFs (Sen-NAC TFs) regulate autumn leaf senescence.
結果2-PtRD26內含子滯留:Age-dependent alternative splicing (AS) caused an intron-retention (IR) event in the pre-mRNA encoding PtRD26, a NAC-TF. This produced a truncated protein PtRD26IR, which functions as a dominant-negative regulator of senescence by interacting with multiple hub Sen-NAC TFs, thereby repressing their DNA-binding activities.
結果3-剪切因子鑑定:Functional analysis of senescence-associated splicing factors identified two U2 auxiliary factors that are involved in AS of PtRD26IR.
結果4-剪切因子驗證:Correspondingly, silencing of these factors decreased PtRD26IR transcript abundance and induced early senescence.
結論:We propose that an age-dependent increase of IR splice variants derived from Sen-NAC TFs is a regulatory program to fine tune the molecular mechanisms that regulate leaf senescence in trees.