Background: Cold stress is one of the main abiotic stresses limiting cucumber (Cucumis sativus L.) growth and production. C-repeat binding factor/Dehydration responsive element-binding 1 protein (CBF/DREB1), containing conserved APETALA2 (AP2) DNA binding domains and two characteristic sequences, are key signaling genes that can be rapidly induced and play vital roles in plant response to low temperature. However, the CBF family has not been systematically elucidated in cucumber, and the expression pattern of this family genes under cold stress remains unclear. Results: In this study, three CsCBF family genes were identified in cucumber genome and their protein conserved domain, protein physicochemical properties, gene structure and phylogenetic analysis were further comprehensively analyzed. Subcellular localization showed that all three CsCBFs were localized in the nucleus. Cis-element analysis of the promoters indicated that CsCBFs might be involved in plant hormone response and abiotic stress response. Expression analysis showed that the three CsCBFs could be significantly induced by cold stress, salt and ABA. The overexpression of CsCBFs in cucumber seedlings enhanced the tolerance to cold stress, and importantly, the transcript levels of CsCOR genes were significantly upregulated in 35S:CsCBFs transgenic plants after cold stress treatment. Biochemical analyses ascertained that CsCBFs directly activated CsCOR genes expression by binding to its promoter, thereby enhancing plant resistance to cold stress. Conclusion: This study provided a foundation for further research on the function of CsCBF genes in cold stress resistance and elucidating its mechanism.

Broussonetia papyrifera has a high lignocellulose content leading to poor palatability and low digestion rate of ruminants. Thus, dynamic profiles of fermentation lignocellulose characteristics, microbial community structure, potential function, and interspecific relationships of B. papyrifera mixing with wheat bran in different ratios: 100:0 (BP100), 90:10 (BP90), 80:20 (BP80), and 65:35 (BP65) were investigated on ensiling days 5, 15, 30, and 50. The results showed that adding bran increased the degradation rate of hemicellulose, neutral detergent fiber, and the activities of filter paper cellulase, endoglucanase, acid protease, and neutral protease, especially in the ratio of 65:35. Lactobacillus, Pediococcus, and Weissella genus bacteria were the dominant genera in silage fermentation, and Pediococcus and Weissella genus bacteria regulated the process of silage fermentation. Compared with monospecific B. papyrifera silage, adding bran significantly increased the abundance of Weissella sp., and improved bacterial fermentation potential in BP65 (p < 0.05). Distance-based redundancy analysis showed that lactic acid bacteria (LAB) were significantly positive correlated with most lignocellulose content and degrading enzymes activities, while Monascus sp. and Syncephalastrum sp. were opposite (p < 0.05). Co-occurrence network analysis indicated that there were significant differences in microbial networks among different mixing ratios of B. papyrifera silage prepared with bran. There was a more complex, highly diverse and less competitive co-occurrence network in BP65, which was helpful to silage fermentation. In conclusion, B. papyrifera ensiled with bran improved the microbial community structure and the interspecific relationship and reduced the content of lignocellulose.

Improvement of low nitrogen (LN) tolerance or nitrogen use efficiency (NUE) in crops is imperative for environment-friendly agriculture development. The basic helix-loop-helix (bHLH) transcription factors are involved in multiple abiotic stresses and are suitable as candidate genes for improving LN tolerance. Few studies were performed on the characterization of the HvbHLH gene family and their function in response to LN stress in barley. In this study, 103 HvbHLH genes were identified through genome-wide analysis. HvbHLH proteins were classified into 20 subfamilies based on phylogenetic analysis in barley, which was supported by conserved motifs and gene structure analysis. The stress-related cis-element analysis in the promoters showed that HvbHLHs are probably involved in multiple stress responses. By phylogenetic analysis of HvbHLHs and bHLHs in other plants, some HvbHLHs were predicted to play roles in response to nutrition deficiency stress. Furthermore, at least 16 HvbHLHs were differentially expressed in two barley genotypes differing in LN tolerance under LN stress. Finally, overexpression of HvbHLH56 enhanced LN stress tolerance in transgenic Arabidopsis, suggesting it is an important regulator in LN stress response. The differentially expressed HvbHLHs identified herein may be valuable for the breeding of barley cultivars with LN tolerance.

The peel color of pomegranates is an important exterior quality that determines market value. Anthocyanins are biosynthesized in the cytosol and then transported to the vacuole for storage. However, the molecular mechanism that determines the color variation between red and white pomegranates remains unclear. In this study, we identified an R2R3-MYB protein (PgMYB1) that interacts with the PgGSTF6 promoter and regulates its transcriptional expression, thus promoting the accumulation of anthocyanins in pomegranate. The expression of PgMYB1 and PgGSTF6 was positively correlated with the anthocyanin content in red and white pomegranates. Further investigation showed that the knockdown of PgMYB1 in red pomegranate ‘Taishanhong’ (TSH), by the virus-induced gene-silencing system, inhibited anthocyanin accumulation. Together, our results indicate that PgMYB1 controls the transport of anthocyanin via PgGSTF6 and thus promotes anthocyanin accumulation in red pomegranates. Our results have a certain reference value for further clarifying the regulation of anthocyanin synthesis and transport in pomegranate fruits.