Korean Journal of Agricultural Science (농업과학연구)

Institute of Agricultural Science, CNU (충남대학교 농업과학연구소)
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Characterization of Phytophthora capsici effector genes and their functional repertoire

  • Arif, Saima (Department of Applied Biology, College of Agriculture & Life Sciences, Chungnam National University) ;
  • Lim, Gi Taek (Department of Applied Biology, College of Agriculture & Life Sciences, Chungnam National University) ;
  • Kim, Sun Ha (Department of Applied Biology, College of Agriculture & Life Sciences, Chungnam National University) ;
  • Oh, Sang-Keun (Department of Applied Biology, College of Agriculture & Life Sciences, Chungnam National University)
  • Received : 2021.08.03
  • Accepted : 2021.08.25
  • Published : 2021.09.01
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Abstract

Phytophthora capsici is one of the most destructive hemibiotrophic pathogens; it can cause blight in chili peppers, and secrete various effector proteins to infect the plants. These effectors contain an N-terminal conserved RXLR motif. Here, we generated full-length RXLR effector coding genes using primer pairs, and cloned them into the pGR106 vector for in planta expression. Two of these genes, PcREK6 and PcREK41 (P. capsici RXLR effector from the Korea isolate), were further characterized. PcREK6 and PcREK41 genes showed that they encode effector proteins with a general modular structure, including the N-terminal conserved RXLR-DEER motif and signal peptide sequences. PcREK6 and PcREK41 expressions were strongly induced when the chili pepper plants (Capsicum annuum) were challenged with P. capsici. These results provide molecular evidence to elucidate the virulence or avirulence factors in chili pepper. Our results also showed that two effectors induce hypersensitive response (HR) cell death when expressed in chili leaves. Cell death suppression assays in Nicotiana benthamiana revealed that most effectors could not suppress programmed cell death (PCD) triggered by Bcl-associated X (BAX) or Phytophthora infestans elicitin (INF1). However, PcREK6 fully suppressed PCD triggered by BAX, while PcREK41 partially suppressed PCD triggered by INF1 elicitin. These results suggest that PcREK effectors from P. capsici interact with putative resistance (R) proteins in planta, and different effectors may target different pathways in a plant cell to suppress pattern-triggered immunity (PTI) or effector-triggered immunity (ETI).

Keywords

Acknowledgement

We thank to the Asia seed Company (Seoul, Korea) for providing the chili pepper cultivars (Jumbo, Jumping, and Jindaegeon). We also thank Korean Agricultural Culture Collection for providing the Phytophthora. capsici isolate. This work was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture and Forestry (IPET) through Crop Viruses and Pests Response Industry Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (Project No. 120086052SB010).

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