Abstract
AAL-toxin is a pathogenicity factor of Alternaria alternata f. sp. lycopersici. AAL-toxin is sphinganine-analog and disturbs ceramide biosynthesis, resulting in the inducing programmed cell death (PCD) in host plants. To investigate candidate genes involved in AAL-toxin-induced cell death, we employed virus-induced gene silencing (VIGS) and Nicotiana umbratica that is sensitive to the AAL-toxin. We have showed that ethylene signaling pathway plays a pivotal role in AAL-toxin-induced cell death and identified NuERF4, which is AP2/ERF transcription factor, as a mediator for AAL-toxin-induced cell death. To further investigate role of ethylene signaling in PCD, we used Arabidopsis thaliana and fumonisin B1 (FB1) that is structural analog of AAL-toxin. To find A. thaliana ERF4 homolog (AEH1), multiple alignment analysis was performed using amino acid sequences of the AP2/ERF domain. In aeh1 mutant, FB1-induced cell death was suppressed. Furthermore, we produced AEH1-overexpressed plants and identified genes up- or down-regulated by AEH1-overexpression by microarray analysis.
