Abstract: Seed acquired vigor during desiccation stage in seed development, different from the previous opinions, new evidence insisted that seed desiccation is not only involved in water loss process, but also as a significant proportion of the gene expression and metabolic signatures of which resemble those characterized seed germination, implied that the preparation of the seeds for germination began already during seed desiccation. The germination of seeds initiated from water-uptake, accompanied by metabolic recovery, then radicle breaked through endosperm and seed coat and other peripheral completed germination. The main contributor of seed germination success is the quality of the messenger RNAs stored during embryo maturation in the mother plant. In addition, proteostasis and DNA integrity play a major role in the germination phenotype. Plant hormone, as a signal, concentration extremely fewer even approximate to zero, was also important for seed dormancy release and germination. Recently, more and more ideas have considened that the ABA/GA ratio regulats the metabolic transition required for germination. GAs, although required for the completion of germination, are not directly involved in many processes taking place during germination like ABA, which occurred at a stage coinciding with or very close to radicle emergence. It appears that reciprocal downregulation of the respective metabolic pathways accounts for a significant part of GA and ABA interplay, and the α-amylase gene, is transcriptionally regulated by both ABA and GA. In addition to the ABA and GA, recently research found IAA finely regulated radicle emerge that more strictly than cotyledons open during seed germination. Auxin action in seed dormancy and germination requires the auxin response factors 10 and 16 to indirectly control the expression of ABI3. Compared with germination in light condition, seedlings germinated in soil will form a specific organization ‘Apical hook’, its main role was to protect the ‘SAM’. Auxin, accumulating at the concave side, was critical for the formation and maintenance of the hook structure, whereas a release of the auxin maximum correlates with hook opening. To improve the vigor, seed were primed before sowing, the key of which was to control seeds very close to radicle emergence but redried before it in time. In fact, seed stored mRNAs and proteins began to perform its function during priming, and also the molecular biological mechanism was "memorized" at the later redried state, so re-imbibed seeds could quickly germinate. Except as toxic molecules, ROS is also involved in the mobilization of storage and endosperm loose as signaling molecules during seed germination, and it is always interacted with hormone molecule ABA and GA, that also controls seed germination via translation and posttranslational modifications. Methionine metabolism is the metabolism core in seed germination and its metabolites widely regulate the physiological and biochemical reaction of seed germination, such as DNA synthesis, protein stability, chromosome structure formation and remodeling, biotin synthesis, and is also interacted with hormone molecule ABA, GA, ETH, and active oxygen or nitrogen. Recently new evidence insisits on the methionine sulfoxide reductase took part in repair system in plant seed longevity, which also might play a role in seed vigor. This article focused on the domestic and foreign research status on seed vigor, and also provided an outlook of the future research hotspots, such as the senses traits in seeds "preharvest", the molecular mechanism about higher vigor seeds but less field emergence, the important role of auxin in radicle breakout, methionine metabolism, and the methods about seed vigor testing, etc.

Key words: seed vigor, germination, hormone, reactive oxygen species, methionine metabolism, -omics