Background OsWRKY62 and OsWRKY76, two close members of WRKY transcription factors, function together as transcriptional repressors. OsWRKY62 is predominantly localized in the cytosol. What are the regulatory factors for OsWRKY62 nuclear translocation? Results In this study, we characterized the interaction of OsWRKY62 and OsWRKY76 with rice importin, OsIMα1a and OsIMα1b, for nuclear translocation. Chimeric OsWRKY62.1-GFP, which is predominantly localized in the cytoplasm, was translocated to the nucleus of Nicotiana benthamiana leaf cells in the presence of OsIMα1a or OsIMαΔIBB1a lacking the auto-inhibitory importin β-binding domain. OsIMαΔIBB1a interacted with the WRKY domain of OsWRKY62.1, which has specific bipartite positively charged concatenated amino acids functioning as a nuclear localization signal (NLS). Similarly, we found that OsIMαΔIBB1a interacted with the AvrPib effector of rice blast fungus Magnaporthe oryzae, which contains a scattered distribution of positively charged amino acids. Furthermore, we identified a nuclear export signal (NES) in OsWRKY62.1 that inhibited nuclear transportation. Overexpression of OsIMα1a or OsIMα1b enhanced resistance to M. oryzae, whereas knockout mutants decreased resistance to the pathogen. However, overexpressing both OsIMα1a and OsWRKY62.1 were slightly more susceptible to M. oryzae than OsWRKY62.1 alone. Ectopic overexpression of OsWRKY62.1-NES fused gene compromised the enhanced susceptibility of OsWRKY62.1 to M. oryzae. Conclusion These results revealed the existence of NLS and NES in OsWRKY62. OsWRKY62, OsWRKY76, and AvrPib effector translocate to nucleus in association with importin α1s through new types of nuclear localization signals for negatively regulating defense responses.

Background/Objectives: Polygonati rhizoma (PR) is a common traditional Chinese medicine that has been used for 2000 years in China, serving as both food and medicine. It is known for various health benefits, including antidiabetic effects, regulation of gut microbiota, and enhancement of immunity. The most popular PR varieties are Polygonatum kingianum Coll. et Hemsl. (PK), Polygonatum sibiricum Red. (PS), Polygonatum cyrtonema Hua (PC), and Polygonatum odoratum (Mill.) Druce (PO). We aimed to determine the differences among these four PR species. Methods: Using an untargeted mass spectrometer we conducted a metabolomic analysis. Results: We detected 2360, 2336, 2381, and 2355 unique polysaccharide, steroid, alkaloid, nucleoside, and peptide metabolites, among which 10, 36, 5, and 26 were specific to PK, PS, PC, and PO, respectively. Differentially expressed polysaccharide, steroid, and alkaloid metabolites were identified in the four species. A total of 61, 56, 61, and 57 carbohydrates were identified in the PK, PS, PC, and PO, respectively; 33, 32, 29, and 30 steroids were identified in the PK, PS, PC, and PO, respectively; and 10, 12, 12, and 11 alkaloids were identified in PK, PS, PC, and PO, respectively. Conclusions: Our findings provide novel insights into the overall metabolome of the four PR species, improve understanding of their functions and effectiveness, and provide a theoretical basis for qualitative evaluation and comprehensive PR applications.

Dendrobium candidum is a traditional Chinese medicinal herb with green and red stems. D. candidum, which has red stems, is highly nutritious. However, there is a need to clarify the mechanisms of transcriptional regulation underlying anthocyanin biosynthesis in D. candidum. In this study, we found that the red stem of D. candidum has a high anthocyanin content and a wide variety of types. Cyanidin derivatives of anthocyanins were found to be responsible for red pigmentation in red leaves. An R3-MYB transcription factor, DcMYB56, which modulates anthocyanin biosynthesis, along with homologs of other plants, was isolated and identified. Compared with that in green stems, DcMYB56 expression in D. candidum red stems markedly increased. The binding of DcMYB56 to the DcCHS8, DcF3′H, DcF3′5′H, and DcANS1 gene promoters controlled DcMYB56 expression levels. The overexpression of DcMYB56 in Arabidopsis thaliana resulted in a red phenotype and substantially increased the anthocyanin content. Our findings suggest that DcMYB56 is important for anthocyanin biosynthesis, which thus sheds new light on the modulation of anthocyanin biosynthesis-associated transcription factors in D. candidum.