Abstract
Potato late blight, caused by the oomycete pathogen Phytophthora infestans, significantly hampers potato production. Recently, a new Resistance to Phytophthora infestans (Rpi) gene, Rpi‐amr1, was cloned from a wild Solanum species, Solanum americanum. Identification of the corresponding recognized effector (Avirulence or Avr) genes from P. infestans is key to elucidating their naturally occurring sequence variation, which in turn informs the potential durability of the cognate late blight resistance. To identify the P. infestans effector recognized by Rpi‐amr1, we screened available RXLR effector libraries and used long read and cDNA pathogen‐enrichment sequencing (PenSeq) on four P. infestans isolates to explore the untested effectors. Using single‐molecule real‐time sequencing (SMRT) and cDNA PenSeq, we identified 47 highly expressed effectors from P. infestans, including PITG_07569, which triggers a highly specific cell death response when transiently coexpressed with Rpi‐amr1 in Nicotiana benthamiana, suggesting that PITG_07569 is Avramr1. Here we demonstrate that long read and cDNA PenSeq enables the identification of full‐length RXLR effector families and their expression profile. This study has revealed key insights into the evolution and polymorphism of a complex RXLR effector family that is associated with the recognition by Rpi‐amr1.
Highlights
Potato late blight, caused by the hemibiotrophic oomycete pathogen Phytophthora infestans, triggered the Irish and European famine in the late 1840s, and still causes severe losses to world potato production.To reduce losses, breeders sought resistance genes in wild relatives of potato
To identify the P. infestans effector recognized by Resistance to Phytophthora infestans (Rpi)-amr1, we screened available RXLR effector libraries and used long read and cDNA pathogen-enrichment sequencing (PenSeq) on four P. infestans isolates to explore the untested effectors
Using single-molecule real-time sequencing (SMRT) and cDNA PenSeq, we identified 47 highly expressed effectors from P. infestans, including PITG_07569, which triggers a highly specific cell death response when transiently coexpressed with Rpi-amr1 in Nicotiana benthamiana, suggesting that PITG_07569 is Avramr1
Summary
Potato late blight, caused by the hemibiotrophic oomycete pathogen Phytophthora infestans, triggered the Irish and European famine in the late 1840s, and still causes severe losses to world potato production. We adapted and improved PenSeq with long read (PacBio) and cDNA sequencing, and extended the list of candidate effectors that could be screened Amongst these additional candidate RXLR genes, we identified Avramr and defined orthologs and paralogs from four different isolates of P. infestans. Our PacBio PenSeq analysis created a rich data set to reveal new Avr variants from different P. infestans isolates, and to quantify their expression profile individually. This facilitates the analysis of the polymorphism of pathogen effectors and their potential differential recognition patterns with the corresponding Rpi genes (Witek et al, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
