Abstract
AAL-toxin is a pathogenicity factor of Alternaria alternata f. sp. Lycopersici, a pathogen of tomato stem canker disease. Little is known about the signaling pathway of AAL-toxin leading to programmed cell death. To dissect the biological function of genes involved in AAL-toxin-induced cell death, we used Nicotiana umbratica that is sensitive to the AAL-toxin, and virus-induced gene silencing (VIGS). We have showed that ethylene signaling plays a pivotal role in AAL-toxin-induced cell death and identified NuERF4 as a component for the cell death signaling. Here, we investigated regulatory mechanism of NuERF4 for transcription using GAL4 cis-element and minimal 35S promoter, indicating that NuERF4 positively activated the transcription. Overexpression of NuERF4 did not induce cell death in N. umbratica, however, accelerated AAL-toxin-induced cell death and disease symptom by the pathogen inoculation. These results suggest that NuERF4 positively regulates genes involved in AAL-toxin cell death.
