The Poaceae family is of great importance to human beings since it comprises the cereal grasses which are the main sources for human food and animal feed. With the rapid growth of genomic data from Poaceae members, comparative genomics becomes a convinent method to study genetics of diffierent species. The SSRs (Simple Sequence Repeats) are widely used markers in the studies of Poaceae for their high abundance and stability. In this study, using the genomic sequences of 9 Poaceae species, we detected 11,993,943 SSR loci and developed 6,799,910 SSR primer pairs. The results show that SSRs are distributed on all the genomic elements in grass. Hexamer is the most frequent motif and AT/TA is the most frequent motif in dimer. The abundance of the SSRs has a positive linear relationship with the recombination rate. SSR sequences in the coding regions involve a higher GC content in the Poaceae than that in the other species. SSRs of 70-80 bp in length showed the highest AT/GC base ratio among all of these loci. The result shows the highest polymorphism rate belongs to the SSRs ranged from 30 bp to 40 bp. Using all the SSR primers of Japonica, nineteen universal primers were selected and located on the genome of the grass family. The information of SSR loci, the SSR primers and the tools of mining and analyzing SSR are provided in the PSSRD (Poaceae SSR Database, http://biodb.sdau.edu.cn/pssrd/ ). Our study and the PSSRD database provide a foundation for the comparative study in the Poaceae and it will accelerate the study on markers application, gene mapping and molecular breeding.

Tobacco seeds are a valuable food oil resource, and tobacco seed oil is rich in nutrients, especially polyunsaturated fatty acids. The aim of this work was to perform a comprehensive study on the chemical constituents, and the antioxidant, anti-inflammatory, and whitening activities of tobacco seed oils (NC89 and BS4). A GC/MS analysis revealed that NC89 and BS4 had 11 and 6 volatile compounds, respectively. The PUFA contents in NC89 and BS4 were 74.98% and 72.84%, respectively. These two tobacco seed oils also presented good radical scavenging capacities with the neutralization of ABTS, OH⁻, and superoxide (O₂⁻) radicals in a concentration-dependent manner. Meanwhile, NC89 and BS4 inhibited reactive oxygen species (ROS) accumulation and cell apoptosis, enhanced SOD and CAT activities, and increased the GSH content in H₂O₂-induced HepG2 cells. In addition, NC89 and BS4 exhibited significant anti-inflammatory activities by inhibiting the expressions of NO, TNF-α, IL-1β, and IL-6 in LPS-induced RAW.264.7 cells through the regulation of the MAPK signaling pathway. Moreover, NC89 and BS4 expressed whitening activities by inhibiting tyrosinase activity and intracellular melanin production. Therefore, tobacco seed oils could be used as an important oil resource for the development of high value-added products.

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.