Differential protein analysis of Heracleum moellendorffii Hance seeds during stratification

Heracleum moellendorffii Hance is a medicinal vegetable species, and the seed dormancy of this species has caused many agricultural problems. One stratification technique involves alternating layers of seeds and substrate to allow post-ripening of dormant seeds under appropriate environmental conditions and to release dormancy. Non-stratified seeds (NS), cotyledon-stage-embryo seeds (CS) and germinated seeds (GS) represent key stages of H. moellendorffii seeds during stratification. To better understand the breaking of dormancy caused by stratification, tandem mass tag (TMT) mass spectrometry (MS)/MS was used to detect proteins among NS, CS and GS. A total of 876 proteins were identified, which were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The results showed that carbohydrate metabolic processes, responses to stress and ribosome biogenesis were the main biological processes. The changes in protein accumulation were validated by qRT-PCR. The results showed that starch, sucrose, pyruvate and fatty acid metabolism played significant roles and that the contents of stored substances were gradually degraded during stratification. This study provides a theoretical basis in terms of proteomics for exploring the post-ripening and germination of H. moellendorffii seeds.