Salt stress is a serious abiotic stress that primarily inhibits plant growth, resulting in severe yield losses. Our previous research found that flavonoids play important roles in A. venetum salt stress tolerance. In response to salt stress, we noted that the flavonoid content was depleted in A. venetum. However, the detailed mechanism is still not clear. In this study, the expression patterns of three flavonoids synthetase genes, AvF3H, AvF3’H, and AvFLS were systemically analyzed under salt stress in A. venetum seedlings. The salt tolerance of transgenic Arabidopsis plants was improved by heterologous overexpression of these synthetase genes. The NBT and DAB staining results as well as H₂O₂ and O₂•^- content analysis revealed that under salt stress, ROS molecules were reduced in transgenic plants compared to WT plants, which corresponded to the activation of the antioxidant enzyme system and an increase in total flavonoid content, particularly rutin, eriodictyol, and naringerin in transgenic plants. External application of flavonoids reduced ROS damage in WT plants just like what we observed in the transgenic plants (without the external application). Additionally, our transcriptome analysis demonstrated that auxin and jasmonic acid biosynthesis genes, as well as signaling transduction genes, were primarily activated in transgenic plants under salt stress, leading to activation of the cell wall biosynthesis or modification genes that promote plant growth. As a result, we investigated the mechanism through flavonoids enhance the salt tolerance, offering a theoretical foundation for enhancing salt tolerance in plants.

Among the largest transcription factor families in plants, bZIPs are crucial for various developmental and physiological processes, particularly abiotic stress resistance. Setaria italica has become a model for understanding stress resistance mechanisms. In this study, we identified 90 bZIP transcription factors in the Setaria italica genome. SibZIPs were classified into 13 groups based on references to Arabidopsis bZIPs. Members in the same group shared similar motifs and gene structure pattern. In addition, gene duplication analysis indenfied 37 pairs of segmental duplicated genes and none tandem duplicated genes in S. italica suggesting segmental duplication contributed to the expansion of the S. italica bZIP gene family. Moreover, the number of SibZIPs genes (39) exhibiting higher expression in roots was significantly more than that in other organs. Twelve SibZIP genes were upregulated in response to dehydration stress. In conclusion, our study advances the current understanding of SibZIP genes and provide a number of candidates for functional analysis of drought tolerance in S. italica.

Abiotic stress has been a great challenge to global food security. To reduce its effects, breeding crops for tolerance to abiotic stresses is a promising strategy. Broomcorn millet is cultivated in arid and semiarid areas with a high degree of abiotic stress tolerance. However, due to the lack of efficient genetic transformation methods for broomcorn millet, the characterization of genes related to abiotic stress tolerance lags behind that of other crop species. Therefore, establishing efficient in vitro regeneration and genetic transformation methods for broomcorn millet is essential. In this study, we used mature seeds of the sequenced variety ‘Longmi 4’ as explants and optimized its in vitro regeneration and genetic transformation methods. The optimal hormone concentrations for embryogenic callus induction medium were 2.5 mg/L 2,4-dichlorophenoxyacetic and 0.5 mg/L 6-benzylaminopurine. The optimal hormone concentrations for shoot regeneration medium were 2 mg/L 6-benzylaminopurine and 0.5 mg/L a-naphthaleneacetic acid. Additionally, the co-cultivation time was 3 days, and the optimal hygromycin concentration for putative transgenic callus selection was 20 mg/L. The transformation efficiency was 21.25% after our modification approach. Here, we present a simple and highly efficient Agrobacterium-mediated genetic transformation protocol for broomcorn millet. Our work provides a tool for the characterization of genes related to important traits, as well as a new strategy for broomcorn millet breeding