Transcriptional regulators involved in responses to volatile organic compounds in plants

Abstract

It has been reported since the 1980s that plants neighboring to herbivore-infested plants in field acquire higher levels of resistance to damages. The current understanding is that it is due to volatile organic compounds (VOCs), released from wounded plants, which trigger defensive responses in neighboring healthy plants. The molecular basis for sensing VOCs in plants, however, is poorly understood. Here, we report the identification of a transcriptional regulatory protein that has a VOC-binding activity and is involved in VOC sensing in tobacco. Via screening for volatiles that induce stress-responsive gene expression in tobacco BY-2 cell and tobacco plants, we found that some sesquiterpenes, caryophyllene analogs, induced stress-responsive gene. These results provide evidence that plants sense molecular species of VOCs, and motivated us focusing on VOC binding molecules to analyze the mechanisms underlying volatile sensing. As a result, we identified TOPLESS-like proteins (TPLs), transcriptional co-repressors, that were specifically bound to the caryophyllene derivative-linked beads. Importantly, when TPLs was overexpressed in BY-2 cell line, stress-responsive gene expression by the caryophyllene was reduced. These results suggest that the interaction of TPLs and caryophyllene analogs lead to the induction of target genes and thus shed light on the mechanism of VOC sensing in plants.