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Article|19 Jan 2022|OPEN
Silencing susceptibility genes in potato hinders primary infection with Phytophthora infestans at different stages
Kaile Sun1,2 , Danny Schipper2 , Evert Jacobsen2 , Richard G.F. Visser2 , Francine Govers3 and Klaas Bouwmeester3,4 ,† , Yuling Bai,2 , ,†
1College of Horticulture, Henan Agricultural University, Nongye Road 63, 450002 Zhengzhou, Henan, China
2Plant Breeding, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
3Laboratory of Phytopathology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
4Biosystematics Group, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
*Corresponding author. E-mail:
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhab058 (2022)
Views: 342

Received: 30 Jan 2021
Accepted: 12 Nov 2021
Published online: 19 Jan 2022


Most potato cultivars are susceptible to late blight disease caused by the oomycete pathogen Phytophthora infestans. Here we report that the genetic loss of host susceptibility is a new source of resistance to prevent or diminish pathogen infection. Previously, we showed that RNAi-mediated silencing of the potato susceptibility (S) genes StDND1StDMR1, and StDMR6 leads to increased late blight resistance. The mechanisms underlying this S-gene-mediated resistance have thus far not been identified. In this study, we examined the infection process of P. infestans in StDND1-, StDMR1-, and StDMR6-silenced potato lines. Microscopic analysis showed that penetration of P. infestans spores was hampered in StDND1-silenced plants. In StDMR1- and StDMR6-silenced plants, P. infestans infection was arrested at a primary infection stage by enhanced cell death responses. Histochemical staining revealed that StDMR1- and StDMR6-silenced plants display elevated ROS levels in cells at the infection sites. Resistance in StDND1-silenced plants, however, seems not to rely on a cell death response as ROS accumulation was found to be absent at most inoculated sites. Quantitative analysis of marker gene expression suggests that the increased resistance observed in StDND1- and StDMR6-silenced plants relies on an early onset of salicylic acid- and ethylene-mediated signaling pathways. Resistance mediated by silencing StDMR1 was found to be correlated with the early induction of salicylic acid-mediated signaling. These data provide evidence that different defense mechanisms are involved in late blight resistance mediated by functional impairment of different potato S-genes.