Abstract
To better understand the molecular control of leaf senescence, we examined transcriptome changes during seasonal leaf senescence in Populus trichocarpa Nisqually-1, the Populus reference genome, growing in its natural habitat. Using monthly (from May to October) transcriptomes for three years (2009, 2015, and 2016), we identified 17,974 differentially expressed genes (DEGs; false discovery rate <0.05; log-fold change cutoff = 0) from 36,007 expressed Populus gene models. A total of 14,415 DEGs were directly related to transitions between four major developmental phases – growth, senescence initiation, reorganization, and senescence termination. These DEGs were significantly (p < 0.05) enriched in 279 gene ontology (GO) terms, including those related to photosynthesis, metabolic process, catalytic activity, protein phosphorylation, kinase activity, pollination, and transport. Also, there were 881 differentially expressed transcription factor (TF) genes from 54 TF families, notably bHLH, MYB, ERF, MYB-related, NAC, and WRKY. We also examined 28 DEGs known as alternative splicing (AS) factors that regulate AS process, and found evidence for a reduced level of AS activity during leaf senescence. Furthermore, we were able to identify a number of promoter sequence motifs associated with leaf senescence. This work provides a comprehensive resource for identification of genes involved in seasonal leaf senescence in trees, and informs efforts to explore the conservation and divergence of molecular mechanisms underlying leaf senescence between annual and perennial species.
Highlights
Leaf senescence is the programmed death of foliage that enables nutrient mobilization from leaf into seeds in annual plants, or into buds, trunk and roots in perennial plants
Identified sequence motifs associated with distinct gene expression patterns chlorophyll biosynthesis and photosynthesis, and upregulation of genes participating in catabolic processes, such as cell wall degradation and lipid catabolism
(3) Previous studies have revealed common regulatory networks controlling the progression of senescence across plant species, the differentially expressed genes (DEGs), gene ontologies (GOs), and transcription factor (TF) identified in this study will strongly overlap with those associated with leaf senescence in other plant species
Summary
Leaf senescence is the programmed death of foliage that enables nutrient mobilization from leaf into seeds in annual plants, or into buds, trunk and roots in perennial plants. [5] In field grown trees, three simultaneously occurring processes, seasonal leaf senescence, bud dormancy, and cold acclimation, are induced by common environmental stimuli, shortened day length and low temperature, there will be overlaps between DEGs identified in this study and dormancy-associated genes (DAGs) and cold-acclimation-associated genes (CAGs) previously reported in Populus. Directed by these hypotheses, we report extensive transcriptome remodeling that both support and extend expectations from previous publications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
