Reactive oxygen species (ROS) play an essential role in the regulation of seed dormancy, germination, and deterioration in plants. The low level of ROS as signaling particles promotes dormancy release and triggers seed germination. Excessive ROS accumulation causes seed deterioration during seed storage. Maintaining ROS homeostasis plays a central role in the regulation of seed dormancy, germination, and deterioration in crops. This study highlights the current advances in the regulation of ROS homeostasis in dry and hydrated seeds of crops. The research progress in the crosstalk between ROS and hormones involved in the regulation of seed dormancy and germination in crops is mainly summarized. The current understandings of ROS-induced seed deterioration are reviewed. These understandings of ROS-dependent regulation on seed dormancy, germination, and deterioration contribute to the improvement of seed quality of crops in the future.

Tobacco is one of the important cash crops in China. It is sensitive to low temperature, especially in the early stage of tobacco seed germination and seedling growth. Low temperature stress directly affects the germination of tobacco seeds, leading to irregular emergence and slow growth of seedlings. Therefore, it is important to improve the vigor and cold tolerance of tobacco. In this study, two cold-sensitive tobacco varieties were primed individually with ZnSO₄, FeSO₄ and Na₂SeO₃ to test the effects of different microelements priming on seed germination. The results showed that under low temperature (11 °C), all three elements could improve tobacco seed vigor and promote seed germination, with selenium priming exhibiting the best effect. Selenium priming significantly increased the seed vigor index of YY97 by 29.60 % and of YY85 by 47.57 %. Moreover, selenium priming could effectively enhance POD activity in seeds, promote the oxidation of phenolic substances and enhance the activities of G-6-PDH and 6-P-GDH in the process of scavenging ROS and converting H₂O₂ to ·O₂^-. The results suggested that selenium played an important role in promoting tobacco seed germination under low temperature.

Seed ageing is an important issue for the long-time seed storage of tobacco. Seed priming has been popularly applied in tobacco production. In this study, the development of molecular marker genes encoding proteins L-isoaspartyl methyltransferase NtPIMT1 and 8-oxoG DNA glycosylase 1 NtOGG1 to detect the degree of seed ageing and the effect of seed priming is conducted in tobacco. Quantitative real-time PCR (qRT-PCR) analysis reveals that relatively higher mRNAs of NtPIMT1 and NtOGG1 are observed in the dry and early germinating seeds. The expressions of NtPIMT1 and NtOGG1 are negatively correlated with the degree of seed damage in non-pelleted and pelleted seeds after accelerated ageing treatments. The early best effects of gibberellin (GA₃) priming on speed and uniform germination are observed in 33 h primed seeds, and relatively lower expressions of NtPIMT1 and NtOGG1 are observed in priming seeds. NtPIMT1 and NtOGG1 genes have potential for use as molecular markers in detecting the seed ageing degree and priming effect of tobacco.

Seed vigor is an important trait for tobacco production. However, the evaluation of seed vigor using molecular biomarkers is scarcely reported in tobacco. In this study, the development of molecular marker isopropylmalate synthase NtIPMS was conducted to detect seed ageing degree and seed priming effect in tobacco. Quantitative real-time PCR (qRT-PCR) analysis showed that the expression of NtIPMS was significantly induced at the initial imbibition stage during seed germination. The NtIPMS expression was positively correlated with the degree of seed ageing in non-pelleted and pelleted seeds. The mRNA level of NtIPMS was gradually increased with the increasing degree of seed ageing. The early best effect of gibberellin priming was observed in 30-h primed seeds, and the highest expression of NtIPMS was observed in 12-h primed seeds. The best stop time-point of seed priming is likely at the time 18 h after the relatively higher NtIPMS expression occurred during seed priming process. The NtIPMS mRNA detection has the potential usage as a potential molecular marker for the evaluation of seed vigor in tobacco.

Cold tolerance at the seed germination stage is a critical trait for tobacco production. However, the mechanism of seed germination under cold stress is largely unknown in tobacco. In this study, we revealed that tobacco isopropylmalate synthase gene NtIPMS negatively regulates seed germination under cold stress. Compared with wild-type (WT) of tobacco, the seed germination and seedling establishment were significantly reduced in overexpressing NtIPMS lines under cold stress. Physiological assays showed that NtIPMS regulates seed germination by influencing the levels of amino acids and reactive oxygen species (ROS) under cold stress. The lower accumulation of stress-associated amino acids and ROS were observed in overexpression NtIPMS line compared with WT under cold stress. The exogenous application of amino acids and hydrogen peroxide (H₂O₂) may be an effective way to enhance seed germination under cold stress in tobacco.

Seed vigor of tobacco (Nicotiana tabacum L.) is established during seed development stage, while its regulators remain largely unknown. Here, a comparative peptidomics analysis of the developing seeds was conducted to reveal the regulators involving the establishment of tobacco seed vigor. The most significant difference of seed vigor was observed between seeds harvested at 20 and 30 days after pollination (DAP), and then the corresponding seeds were collected separately for peptidomics analysis. A total of 2932 and 2812 nonredundant peptides were identified in seeds harvested at 20 and 30 DAP, respectively. In which, 349 differentially expressed peptides (DEPs) were characterized. To explore the potential functions of these DEPs, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were further analyzed according to their precursor proteins. Most DEP precursor proteins were involved in response to abiotic stimulus, response to water, and protein processing in endoplasmic reticulum. Further, the peptides derived from the precursor proteins, such as late embryogenesis abundant (LEA) protein, heat shock protein, peroxiredoxin, and globulin proteins, may regulates the establishment of seed vigor by influencing reactive oxygen species. The results provide a foundation for further exploration of the peptides functions on the establishment of seed vigor in tobacco.