The transcriptional events and their relationship to physiological changes during poplar seed germination and post-germination

Chunpu Qu,Hongwei Zhao ,Jinyuan Chen,Jiahuan Huang,Xu Zhang ,Xiankui Quan ,Zhuang Zuo,Xiuli Zhang ,Peng Zhang,Xue Sun ,Chengjun Yang,Guanjun Liu

doi:10.1186/s12864-019-6180-5

Abstract

BackgroundSeed germination, the foundation of plant propagation, involves a series of changes at the molecular level. Poplar is a model woody plant, but the molecular events occurring during seed germination in this species are unclear.ResultsIn this study, we investigated changes in gene transcriptional levels during different germination periods in poplar by high-throughput sequencing technology. Analysis of genes expressed at specific germination stages indicated that these genes are distributed in many metabolic pathways. Enrichment analysis of significantly differentially expressed genes based on hypergeometric testing revealed that multiple pathways, such as pathways related to glycolysis, lipid, amino acid, protein and ATP synthesis metabolism, changed significantly at the transcriptional level during seed germination. A comparison of ΣZ values uncovered a series of transcriptional changes in biological processes related to primary metabolism during poplar seed germination. Among these changes, genes related to CHO metabolism were the first to be activated, with subsequent expression of genes involved in lipid metabolism and then those associated with protein metabolism. The pattern of metabolomic and physiological index changes further verified the sequence of some biological events.ConclusionsOur study revealed molecular events occurring at the transcriptional level during seed germination and determined their order. These events were further verified by patterns of changes of metabolites and physiological indexes. Our findings lay a foundation for the elucidation of the molecular mechanisms responsible for poplar seed germination.

Highlights

Seed germination, the foundation of plant propagation, involves a series of changes at the molecular level
Identification of genes expressed at different germination stages A total of 27,359 differentially expressed genes were identified during poplar seed germination, which differ significantly from 0 h expression in at least one period
The respiratory rate was high at 0.75 h, and another peak appeared at 48 h; these results indicate that the Adenosine triphosphate (ATP) synthesis function had recovered after 0.75 h of seed germination, with only partial gene activity required for recovery [33]

Summary

Introduction

The foundation of plant propagation, involves a series of changes at the molecular level. Poplar is a model woody plant, but the molecular events occurring during seed germination in this species are unclear. Seed germination, which comprises a series of ordered physiological and morphogenetic processes beginning with seed imbibition, is the starting point for higher plant growth and development [1,2,3,4,5,6]. Seed germination involves a series of complex changes in gene transcription and translation and protein modification. In recent years, seed germination processes have been explored in species such as Arabidopsis [10,11,12], soybean [13] and rice [14], with only a few such studies focusing on woody plants. The molecular characteristics of seeds of woody plants at different stages of germination, especially the woody model plant poplar, have not been studied in detail

Methods

Results

Discussion

Conclusion