Comparative physiological and transcriptomic profiles reveal regulatory mechanisms of soft rot disease resistance in Amorphophallus spp.

Abstract

Amorphophallus spp. are important industrial crops in Southwest China. Unfortunately, bacterial disease is one of the factors limiting the development of the Amorphophallus spp. industry. Soft rot can be caused by the pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) and leads to large-scale losses in Amorphophallus spp. quality and production. However, the mechanisms underlying the response of Amorphophallus spp. to Pcc remain largely unknown. This study compared two species of Amorphophallus, A. muelleri and A. konjac, to explore Pcc resistance by combined physiological and transcriptome analysis. On the basis of phenotype analysis, A. muelleri exhibited higher resistance to Pcc than A. konjac. Moreover, the transcriptomes of A. muelleri and A. konjac were assembled, and differentially expressed genes (DEGs) were annotated. Significant categories including the plant hormone transduction pathway, phenylpropanoid biosynthesis pathway and plant pathogen interaction pathway were identified. Among these pathways, small auxin upregulated RNA (SAUR), ethylene responsive transcription factor 1 (ERF1), 4-coumarate-CoA ligase (4CL), peroxidase (POD), WRKY transcription factor, Ca2+ sensor-related and mitogen-activated protein kinase (MAPK) genes were upregulated in A. muelleri, which may be involved in the regulation of energy, oxidative stress and signal transduction upon exposure to Pcc infection. The transcription levels of four selected genes were further verified by quantitative real-time PCR. Overall, this study identifies several critical genes involved in resistance to soft rot disease in Amorphophallus spp. and provides a theoretical foundation for identifying potential targets for metabolic engineering for disease control.