Role of BASIC PENTACYSTEIENE transcription factors in a subset of cytokinin signaling responses (Plant J)

When cytokinin binds to its receptor AHKs (Arabidopsis Histidine Kinase), the signal is transduced through AHPs (Arabidopsis Histidine-containing Phosphotransfer protein) and eventually to type-B ARRs (Arabidopsis Response Regulators) transcription factors (TFs). Type-B ARR TFs mediate the primary cytokinin response, but the cytokinin response also acts through other TFs in different cellular contexts. In this article, Shanks et al. studied the role of BBR/BPC (BARLEY B–RECOMBINANT/BASIC PENTACYSTEINE) TFs in cytokinin responses. The authors demonstrated that multi-BPC mutants (bpc1,2,3,4,6 and bpc1,2,3,4,6,7) have reduce cytokinin sensitivity and altered transcription of a subset of cytokinin-regulated genes. Yeast two-hybrid assays confirmed that BPC1 and BPC6 interact with type-B ARRs (ARR4 and ARR5), and ChIP-Seq data demonstrated that ARR10 and BPC6 bind a common promoter element in a number of genes. Furthermore, there is an overlap in genes altered in the bpc mutant with those affected in other TF mutants including CRFs (cytokinin response factors) and type-A ARRs. Altogether these data suggest that BPCs work along with known type-B ARRs in the transcriptional regulation of cytokinin responses. (Summary by Arif Ashraf @aribidopsis) Plant Journal 10.1111/tpj.13962