Physiological and dynamic transcriptome analysis of two potato varieties reveal response of lignin and MAPK signal to dry rot caused by Fusarium sulphureum

Abstract

Potato dry rot (PDR), caused by Fusarium sulphureum (F. sulphureum) is a serious storage disease and can cause post-harvest rotting and seed piece decay after planting. Physiological and dynamic transcriptome analyses were detected in two PDR-resistant varieties (LS and Atl) to explore the resistant mechanism of potato. The phenylalanine ammonia lyase (PAL) and lignin content rapidly increased after infection at 0.5, 1, 2, 4, 8, 16 days post inoculation (dpi). Meanwhile, the common up-regulated differentially expressed genes (DEGs) were 1025, 1334 and 1394 in LS and Atl at 1, 3, 7 dpi (vs 0 dpi), respectively. STEM (Short Time-series Expression Miner software) and KEGG enrichment analysis revealed that “lignin synthesis-related pathways” and “MAPK signaling pathway-plant” were significantly enriched in the two varieties. The high expressions of PAL, 4CL, CAD and POD genes promoted the synthesis of lignin in the downstream of the pathway, which was filled to the secondary cell wall to increase the resistance to PDR. In addition, FLS2 gene perceived F. sulphureum infection to initiate MAPK cascades signal transduction, and subsequently up-regulated PR1 defensive genes to respond to pathogen attack. These novel findings elucidate the mechanism of dry rot at the transcriptomic level for the first time, and also provide candidate genes for molecular assisted screening and breeding of resistance to PDR.