NtbHLH49, a jasmonate-regulated transcription factor, negatively regulates tobacco responses to Phytophthora nicotianae .

Tobacco black shank caused by is a devastating disease that causes huge losses to tobacco production across the world. Investigating the regulatory mechanism of tobacco resistance to is of great importance for tobacco resistance breeding. The jasmonate (JA) signaling pathway plays a pivotal role in modulating plant pathogen resistance, but the mechanism underlying JA-mediated tobacco resistance to remains largely unclear. This work explored the responses of common tobacco cultivar TN90 using plants with RNAi-mediated silencing of (encoding the perception protein of JA signal), and identified genes involved in this process by comparative transcriptome analyses. Interestingly, the majority of the differentially expressed bHLH transcription factor genes, whose homologs are correlated with JA-signaling, encode AtBPE-like regulators and were up-regulated in -RI plants, implying a negative role in regulating tobacco response to . A subsequent study on NtbHLH49, a member of this group, showed that it's negatively regulated by JA treatment or infection, and its protein was localized to the nucleus. Furthermore, overexpression of decreased tobacco resistance to , while knockdown of its expression increased the resistance. Manipulation of expression also altered the expression of a set of pathogen resistance genes. This study identified a set of genes correlated with JA-mediated tobacco response to , and revealed the function of AtBPE-like regulator NtbHLH49 in regulating tobacco resistance to this pathogen, providing insights into the JA-mediated tobacco responses to .