Abstract
BACKGROUND: As an important plant source of food and edible oils, pecans are rich in metabolites. Few studies have focused on metabolites involved in pecan seed germination at different temperatures. RESULTS: In our study, we germinated pecan seeds at different temperatures and found that, the germination rate and water content were highest at 30°C. It was found that the radicle of pecan seeds could sense seed coat cracking by observing the microstructure and cell ultra-structure of the seeds at the early stage of germination. We compared the metabolomes of seeds at different temperatures with different germination processes. A total of 349 metabolites were identified, including 138 primary metabolites and 211 secondary metabolites. KEGG enrichment analysis indicated that the differential metabolites were mainly enriched in the metabolic pathways, amino acid synthesis pathways and ABC transporters. Using weighted gene co-expression network analysis (WGCNA), three modules of closely related metabolites were identified. In the brown module, most of hub metabolites were amino substances, whereas in the blue module, many hub metabolites were sugars. CONCLUSIONS: Amino acids and carbohydrates play an important role in pecan seed germination. Differential metaboliteanalysis showed that 30°C was the temperature at which metabolites differed most significantly. This study provides useful information for further research on the seedling establishment of pecan seeds.