Abstract
BackgroundMicroRNAs play pivotal roles in plant vegetative phase change and flowering induction via integrating into multiple flowering pathways. Lilium × formolongi is an important ornamental lily cultivar that can flower within one year after sowing. However, it remains unresolved how miRNA-mediated regulation networks contribute to the L. × formolongi characteristics of a short vegetative growth period and rapid flowering.ResultsIn this study, the small RNA libraries and one degradome library were constructed for L. × formolongi during vegetative growth and flowering initiation, and 366 conserved miRNAs and 32 novel miRNAs were identified. Additionally, 84 miRNAs were significantly differentially expressed during development. A total of 396 targets of 185 miRNAs were identified and validated through degradome sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that functions of the targets were top enriched in the cold and cadmium ion responses, pentose phosphate pathway and carbon fixation in photosynthetic organisms. Furthermore, among 23 differentially expressed miRNA-target pairs, the miR156s-LfSPL2, miR172a-LfAP2 and miR164a-LfNAC pairs as well as miR159a-LfSPL2 were found to be relevant to flowering based on the correlation analysis of expression profiles in the miRNA libraries, degradome and transcriptome. A coexpression regulatory network focused on differentially expressed pairs was also constructed by WGCNA, and 14 miRNAs were considered putative key miRNAs during vegetative development and flowering induction. miR156a/ d/ e showed particularly strong relationships with other miRNAs in the coexpression network.ConclusionsThis study provides cues for the further exploration of the regulatory mechanisms of short vegetative development and flowering in L. × formolongi.
Highlights
MicroRNAs play pivotal roles in plant vegetative phase change and flowering induction via integrating into multiple flowering pathways
In the annual plant Arabidopsis thaliana, external factors such as day length and temperature affect the photoperiod and vernalization pathways [5]. They control phase transitions and flowering time in coordination with ageing, gibberellic acid (GA), trehalose 6-phosphate (T6P) and autonomous pathways governed by endogenous factors including age, hormones and carbohydrate status [5, 6]
High-throughput Small RNA (sRNA) sequencing in L. × formolongi To explore comprehensive miRNA data during L. × formolongi development, 15 small RNA libraries were constructed and sequenced from leaf and stem meristem tissues collected at five developmental stages (VJ_I, VJ_II, FI_I, FI_II and FD) (Additional file 1, Fig. S1, S2)
Summary
MicroRNAs play pivotal roles in plant vegetative phase change and flowering induction via integrating into multiple flowering pathways. Lilium × formolongi is an important ornamental lily cultivar that can flower within one year after sowing It remains unresolved how miRNA-mediated regulation networks contribute to the L. Lilium (Liliaceae family) is an important genus including crops that are valued for their ornamental characteristics, edible bulbs and medical use. They can be propagated by either sexual or asexual propagation. In the annual plant Arabidopsis thaliana, external factors such as day length and temperature affect the photoperiod and vernalization pathways [5] They control phase transitions and flowering time in coordination with ageing, gibberellic acid (GA), trehalose 6-phosphate (T6P) and autonomous pathways governed by endogenous factors including age, hormones and carbohydrate status [5, 6]. A large number of studies suggest that miRNAs are integrated into flowering pathways, in which they perform orchestrated functions [7]
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