Summary The secondary cell wall is an important carbon sink in higher plants and its biosynthesis requires coordination of metabolic fluxes in the phenylpropanoid pathway. In Arabidopsis (Arabidopsis thaliana), MYB75 and the KNOX transcription factor KNAT7 form functional complexes to regulate secondary cell wall formation in the inflorescence stem. However, the molecular mechanism by which these transcription factors control different branches of the phenylpropanoid pathway remains poorly understood in woody species. We isolated an R2R3‐MYB transcription factor MYB6 from Populus tomentosa and determined that it was expressed predominately in young leaves. Overexpression of MYB6 in transgenic poplar upregulated flavonoid biosynthetic gene expression, resulting in significantly increased accumulation of anthocyanin and proanthocyanidins. MYB6‐overexpression plants showed reduced secondary cell wall deposition, accompanied by repressed expression of secondary cell wall biosynthetic genes. We further showed that MYB6 interacted physically with KNAT7 and formed functional complexes that acted to repress secondary cell wall development in poplar and Arabidopsis. The results provide an insight into the transcriptional mechanisms involved in the regulation of the metabolic fluxes between the flavonoid and lignin biosynthetic pathways in poplar.

Intravascular large B-cell lymphoma (IVLBCL) is a rare form of non-Hodgkin’s lymphoma, and is divided into Western and Asian variants. The latter is rarely found to have neurological system involvement. In China, there have only been a few diagnosed cases of IVLBCL. Here, we present a Chinese case of Asian-variant IVLBCL with neurological symptoms. A 32-year-old Chinese man presented with bilateral lower limb numbness and persistent fever. He also complained of difficulties in urination and defecation. In addition, splenomegaly and pancytopenia were observed. We identified 3% dysplastic lymphocytes in his peripheral blood film, and his bone marrow biopsy led to a diagnosis of Asian-variant IVLBCL. Lumbar spine magnetic resonance imaging, which revealed an edematous spinal cord, further confirmed neurological involvement. The patient refused treatment from the time of diagnosis, and died 2 months after being discharged. IVLBCL is a highly aggressive but nonspecific clinical manifestation that is difficult to diagnose; therefore, a greater understanding of the disease is needed. The current first-line therapy involves R-CHOP combination therapy (cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab); however, the overall prognosis of IVLBCL remains poor.