A pair of nuclear factor Y transcription factors act as positive regulators in jasmonate signaling and disease resistance in Arabidopsis.

The plant hormone jasmonate (JA) regulates plant growth and immunity by orchestrating a genome-wide transcriptional reprogramming. In the resting stage, JASMONATE-ZIM DOMAIN (JAZ) proteins act as main repressors to regulate the expression of JA-responsive genes in the JA signaling pathway. However, the mechanisms underlying de-repression of JA-responsive genes in response to JA treatment remain elusive. Here, we report two nuclear factor Y transcription factors NF-YB2 and NF-YB3 (thereafter YB2 and YB3) play key roles in such de-repression in Arabidopsis. YB2 and YB3 function redundantly and positively regulate plant resistance against the necrotrophic pathogen Botrytis cinerea, which are specially required for transcriptional activation of a set of JA-responsive genes following inoculation. Furthermore, YB2 and YB3 modulated their expression through direct occupancy and interaction with histone demethylase Ref6 to remove repressive histone modifications. Moreover, YB2 and YB3 physically interacted with JAZ repressors and negatively modulated their abundance, which in turn attenuated the inhibition of JAZ proteins on the transcription of JA-responsive genes, thereby activating JA response and promoting disease resistance. Overall, our study reveals the positive regulators of YB2 and YB3 in JA signaling by positively regulating transcription of JA-responsive genes and negatively modulating the abundance of JAZ proteins.

Genetic and epigenetic basis of phytohormones control of floral transition in plants.

The timing of the developmental transition from the vegetative to the reproductive stages is critical for angiosperm and fine-tuned by the integration of endogenous factors and external environmental cues to ensure proper and successful reproduction. Plants have evolved sophisticated mechanisms to response to diverse environmental or stress signals, which may be mediated by plant hormones which coordinate their flowering time. Endogenous and exogenous phytohormones such as gibberellin (GA), auxin, cytokinin (CK), jasmonate (JA), abscisic acid (ABA), ethylene (ET), brassinosteroids (BR) and the cross-talk among them are critical for the precise regulating of flowering time. Recent studies on the model flowering plant Arabidopsis thaliana revealed that diverse transcription factors and epigenetic regulators play key roles in the phytohormones that regulate floral transition. This review aims to summarize current knowledge on the genetic and epigenetic mechanisms that underlying the phytohormone control of floral transition in Arabidopsis, offering insights into how these processes are regulated and their implications for plant biology.